My exhaust experiences
#1
09-13-2007, 03:44 PM
My exhaust experiences
Every few weeks I get a PM from some one asking for advice on various exhaust components. I'm a bit tired of responding with basically the same answers time and again, so I though I'd start a thread where I could share the experiences and impressions that I've gained over the past couple of years.
My car is an 05 6MT revup sedan. My first exhaust mod was a midpipe from a 350z. At the time, Coupe midpipes were going for $125 or more, plus shipping. I knew a local z owner and grabbed his midpipe for $25. I then paid $75 for an extension to be welded and the midpipe installed.
Configuration 1 - Midpipe:
The coupe midpipe is a popular mod for the sedan guys, particularly the 03/04 guys. But with the 05 model, the sedan midpipe lost a bit of heft, and had an improved sound IMO. Many 05+ owners have complained that there is little to no difference, except for more drone, between the 05/06 sedan midpipe and coupe midpipe. I'll admit that it wasn't a drastic change, and I don't think that there were any gains whatsoever, but it was worth $100 for a little more volume, plus there was now a euro flavor to the exhaust.
Configuration 2 - Midpipe + Kinetix Cats:
A few months later, I picked up a set of used Kinetix cats. I installed them myself, and had problem after problem with fitment. The cats did not support the factory cat brace, and the driver's side cat literally rested against the shell of the car. I removed the heat shields, and even took a crowbar to the underside of the car. All this helped, but I could never totally fix the metal-on-metal sound the cats made under acceleration. The combination of the Kinetix cats and the 350z midpipe sounded great. Volume still wasn't where I wanted it to be(I wanted it loud dammit), but better than stock or the midpipe alone. The tone was deeper, but not obnoxious, and there wasn't even a hint of rasp. The note was decidedly even more euro. I thought I might have picked up a little in the midrange, but it was hard to tell. After the cats, midpipe, ztube and drop-in filter, I had picked up 7hp at peak and 15tq over stock. My final numbers were 250/227. With these cats, my best 1/4 time was a 14.0@100mph in 35 degree weather.
Configuration 3 - Midpipe + Crawford Cats:
A couple of months later, I picked up some used Crawford cats and sold my Kinetix. The crawfords had zero fitment issues. The sound was much deeper than the Kinetix, but the exhaust had lost much of the euro tone. With the midpipe, the Crawford units were just a low deep tone. Drone was also up a bit over the Kinetix, with still no hint of rasp. When I first drove the car after finishing up the install, I immediately felt more low-end torque(<2k), and the midrange(2k-4k) felt much stronger as well. Up top, I really couldn't tell a difference. About 6 weeks after I had them installed, I finally had another dyno performed, and this time I was back down to near stock levels. This time I could only manage 241/222. Same dyno, same operators. It seemed the crawfords cost me ~8.5hp and ~5.5tq. I still felt the car was faster, but I can't explain the dyno numbers. And despite the measured losses, I ended up turning a 13.7@102mph in 25 degree weather. These cats, with a 10 degree difference in weather, were good for almost 2mph over my Kinetix.
Configuration 4 - Crawford Cats + Stillen Gen1:
I next installed an mrev+ and a first generation Stillen catback. When I cranked the car, I was just floored. The sound was deep and very full. If one could equate sound with size, it would be best described as enormous. I hadn't believed replacing the midpipe and rear muffler would make such a difference. There was still no rasp, none at all, but the drone could rattle your teeth. In fact, the drone was so bad that I started noticing an assortment of interior buzzes, like the sun visors and the seat belts while under load. It turns out that I saw almost no gains whatsoever from the exhaust and the mrev+. During this time I wasn't going to the 1/4 track, but my visits to the 1/8 showed no marked difference from my previous setup.
Configuration 5 - Stock Cats + Stillen Gen1:
When I found that I was not making any more power, I observed that I was running very lean. I tried removing the cats for a couple of months. Dynos showed almost no differences, though I felt like I had lost quite a bit of low end torque. The sound of the exhaust married to the stock cats was nice: drone was reduced by a good margin, and the tone wasn't nearly as deep. The Stillen sedan exhaust has always been deep, but by itself, it had more fidelity.
I ended up reinstalling the cats, and with the addition of a Stillen airbox, I saw very small gains versus the k&n and stock cats. Which again was at odds versus my butt-dyno; when the cats were reinstalled, I immediately noticed more torque all the way to 4 grand.
At this point people are going to question my seemingly random results. My opinion is that by themselves, or to a car very close to stock, cats show very nice gains and the $/hp is more effective than later. But when one has a car with a fair number of mods, the gains from cats start to approach 0.
Configuration 6 - Kinetix Resontated Pipes + Stillen Exhaust:
I was hungry for more NA power, and decided to try some test pipes. I had followed the progress of a user on my350z, thawk, that gained 8hp on his revup when he went from Crawford cats to test pipes. I got some Kinetix Resonated test pipes, and after almost 3 days of wrenching, oiling, cursing, urging, cajoling, and finally begging, I got all of the bolts out. When I took the car for a drive, torque felt the same, but I really felt like I saw some decent gains way up top. Volume also increased, but not nearly as much as I had thought. Everybody talks about the difference in volume between test pipes and hiflow cats. I'll tell the you difference in volume is less than that of stock cats and hiflow cats. But with that volume came increased drone, as well as dreaded rasp. I went with resonated test pipes to try to reduce the rasp. I have to say the rasp is awful, and gets on my nerves from time to time. It certainly doesn't fit the personality of an Infiniti sedan. Fortunately, the rasp is only there between ~3300 and ~4400rpms; a very narrow range, and only under >50% load. You'll never notice the rasp in everyday driving, though the drone is always there. The drone was most significant between 2600 and 3000 rpms, which is the heart of cruising rpms for me on the interstate. The drone was so bad that it sometimes gave me headaches, and Cheryl refused to ride in my car on the interstate. And this time the dyno finally agreed with me: I did pick up a little bit of power up top, though only after 5600rpms. At peak, the difference was 4.5hp. After peak, it was 5hp all the way till redline. So the gains were there, just not very usable.
Configuration 7 - Ichiba Headers + Kinetix Resontated Pipes + Stillen Exhaust:
When I first cranked up the car after the headers were installed, I was surprised to find the exhaust tone was even lower. I didn't think it could sound so deep. I was also surprised to find that the volume was the same. That's right: the exhaust was no louder than with the stock manifolds. The rasp is still there, in the exact same rpm range. There's still some drown at 2k rpms, but it's about what it was with the stock midpipe, just louder. Surprisingly, the drone has shifted all the way up until an indicated 3300rpms or so, and at that only when under a heavy load. Over the summer we drove from Birmingham to Indianapolis, and we were following friends cruising at 90rpms, which put us smack dab in the middle of the drone in top gear. That was a mistake. I'll never do that again.
I hope the thread has been helpful for some one. If any one has more specific questions, feel free to ask.
My car is an 05 6MT revup sedan. My first exhaust mod was a midpipe from a 350z. At the time, Coupe midpipes were going for $125 or more, plus shipping. I knew a local z owner and grabbed his midpipe for $25. I then paid $75 for an extension to be welded and the midpipe installed.
Configuration 1 - Midpipe:
The coupe midpipe is a popular mod for the sedan guys, particularly the 03/04 guys. But with the 05 model, the sedan midpipe lost a bit of heft, and had an improved sound IMO. Many 05+ owners have complained that there is little to no difference, except for more drone, between the 05/06 sedan midpipe and coupe midpipe. I'll admit that it wasn't a drastic change, and I don't think that there were any gains whatsoever, but it was worth $100 for a little more volume, plus there was now a euro flavor to the exhaust.
Configuration 2 - Midpipe + Kinetix Cats:
A few months later, I picked up a set of used Kinetix cats. I installed them myself, and had problem after problem with fitment. The cats did not support the factory cat brace, and the driver's side cat literally rested against the shell of the car. I removed the heat shields, and even took a crowbar to the underside of the car. All this helped, but I could never totally fix the metal-on-metal sound the cats made under acceleration. The combination of the Kinetix cats and the 350z midpipe sounded great. Volume still wasn't where I wanted it to be(I wanted it loud dammit), but better than stock or the midpipe alone. The tone was deeper, but not obnoxious, and there wasn't even a hint of rasp. The note was decidedly even more euro. I thought I might have picked up a little in the midrange, but it was hard to tell. After the cats, midpipe, ztube and drop-in filter, I had picked up 7hp at peak and 15tq over stock. My final numbers were 250/227. With these cats, my best 1/4 time was a 14.0@100mph in 35 degree weather.
Configuration 3 - Midpipe + Crawford Cats:
A couple of months later, I picked up some used Crawford cats and sold my Kinetix. The crawfords had zero fitment issues. The sound was much deeper than the Kinetix, but the exhaust had lost much of the euro tone. With the midpipe, the Crawford units were just a low deep tone. Drone was also up a bit over the Kinetix, with still no hint of rasp. When I first drove the car after finishing up the install, I immediately felt more low-end torque(<2k), and the midrange(2k-4k) felt much stronger as well. Up top, I really couldn't tell a difference. About 6 weeks after I had them installed, I finally had another dyno performed, and this time I was back down to near stock levels. This time I could only manage 241/222. Same dyno, same operators. It seemed the crawfords cost me ~8.5hp and ~5.5tq. I still felt the car was faster, but I can't explain the dyno numbers. And despite the measured losses, I ended up turning a 13.7@102mph in 25 degree weather. These cats, with a 10 degree difference in weather, were good for almost 2mph over my Kinetix.
Configuration 4 - Crawford Cats + Stillen Gen1:
I next installed an mrev+ and a first generation Stillen catback. When I cranked the car, I was just floored. The sound was deep and very full. If one could equate sound with size, it would be best described as enormous. I hadn't believed replacing the midpipe and rear muffler would make such a difference. There was still no rasp, none at all, but the drone could rattle your teeth. In fact, the drone was so bad that I started noticing an assortment of interior buzzes, like the sun visors and the seat belts while under load. It turns out that I saw almost no gains whatsoever from the exhaust and the mrev+. During this time I wasn't going to the 1/4 track, but my visits to the 1/8 showed no marked difference from my previous setup.
Configuration 5 - Stock Cats + Stillen Gen1:
When I found that I was not making any more power, I observed that I was running very lean. I tried removing the cats for a couple of months. Dynos showed almost no differences, though I felt like I had lost quite a bit of low end torque. The sound of the exhaust married to the stock cats was nice: drone was reduced by a good margin, and the tone wasn't nearly as deep. The Stillen sedan exhaust has always been deep, but by itself, it had more fidelity.
I ended up reinstalling the cats, and with the addition of a Stillen airbox, I saw very small gains versus the k&n and stock cats. Which again was at odds versus my butt-dyno; when the cats were reinstalled, I immediately noticed more torque all the way to 4 grand.
At this point people are going to question my seemingly random results. My opinion is that by themselves, or to a car very close to stock, cats show very nice gains and the $/hp is more effective than later. But when one has a car with a fair number of mods, the gains from cats start to approach 0.
Configuration 6 - Kinetix Resontated Pipes + Stillen Exhaust:
I was hungry for more NA power, and decided to try some test pipes. I had followed the progress of a user on my350z, thawk, that gained 8hp on his revup when he went from Crawford cats to test pipes. I got some Kinetix Resonated test pipes, and after almost 3 days of wrenching, oiling, cursing, urging, cajoling, and finally begging, I got all of the bolts out. When I took the car for a drive, torque felt the same, but I really felt like I saw some decent gains way up top. Volume also increased, but not nearly as much as I had thought. Everybody talks about the difference in volume between test pipes and hiflow cats. I'll tell the you difference in volume is less than that of stock cats and hiflow cats. But with that volume came increased drone, as well as dreaded rasp. I went with resonated test pipes to try to reduce the rasp. I have to say the rasp is awful, and gets on my nerves from time to time. It certainly doesn't fit the personality of an Infiniti sedan. Fortunately, the rasp is only there between ~3300 and ~4400rpms; a very narrow range, and only under >50% load. You'll never notice the rasp in everyday driving, though the drone is always there. The drone was most significant between 2600 and 3000 rpms, which is the heart of cruising rpms for me on the interstate. The drone was so bad that it sometimes gave me headaches, and Cheryl refused to ride in my car on the interstate. And this time the dyno finally agreed with me: I did pick up a little bit of power up top, though only after 5600rpms. At peak, the difference was 4.5hp. After peak, it was 5hp all the way till redline. So the gains were there, just not very usable.
Configuration 7 - Ichiba Headers + Kinetix Resontated Pipes + Stillen Exhaust:
When I first cranked up the car after the headers were installed, I was surprised to find the exhaust tone was even lower. I didn't think it could sound so deep. I was also surprised to find that the volume was the same. That's right: the exhaust was no louder than with the stock manifolds. The rasp is still there, in the exact same rpm range. There's still some drown at 2k rpms, but it's about what it was with the stock midpipe, just louder. Surprisingly, the drone has shifted all the way up until an indicated 3300rpms or so, and at that only when under a heavy load. Over the summer we drove from Birmingham to Indianapolis, and we were following friends cruising at 90rpms, which put us smack dab in the middle of the drone in top gear. That was a mistake. I'll never do that again.
I hope the thread has been helpful for some one. If any one has more specific questions, feel free to ask.
#3
09-13-2007, 04:55 PM
#4
09-13-2007, 05:04 PM
#6
09-13-2007, 09:40 PM
Join Date: Mar 2006
Location: Woodstock, GA
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
Awesome write up Trey. I just picked up a set of used DC SS headers off my350z for $250 shipped 
For that price and me doing the install I wont be disappointed if i don't gain much. (I also picked up a UTEC for tuning). Now I want to get a set of High Flow Cats before I have the car tuned. It sounds like the Kinetix did ok on your car but the quality and fitament were not up to par, and really I would expect that out of one of the most affordable HFCs for our cars.
It sounds like you didn't care how loud the was, just wanted a good sound. I'm a bit of the opposite and looking for minimal drone, NO rasp, and moderately low volume. This is why I'm staying with the OEM cat back and put the G mid pipe on to help with weight. With that said, it sounds like the Crawfords may be the way to go? I cant believe you lost power on the dyno. Since you picked up another 2mph in the 1/4 you were obviously making more power. Guessing they may have made some adjustments (maybe calibration?) to the dyno that affected over all output. Most people say that the Dyno is simply a tuning tool and not to worry about the numbers but rather the track performance. You obviously got better track numbers and also said yourself that the car felt better so im sure you gained power. Too bad you couldn't have dynoed back to back on the same day with the two sets of HFCs.
Sharif (FORGED) recommended the Random Tech's. These are pretty close in price to the Crawfords, have you heard anything good or bad between them? Another recommendation by a forum member was the FI & HopUP racing HFCs. Any thoughts are much appreciated.
Aubrey
For that price and me doing the install I wont be disappointed if i don't gain much. (I also picked up a UTEC for tuning). Now I want to get a set of High Flow Cats before I have the car tuned. It sounds like the Kinetix did ok on your car but the quality and fitament were not up to par, and really I would expect that out of one of the most affordable HFCs for our cars. It sounds like you didn't care how loud the was, just wanted a good sound. I'm a bit of the opposite and looking for minimal drone, NO rasp, and moderately low volume. This is why I'm staying with the OEM cat back and put the G mid pipe on to help with weight. With that said, it sounds like the Crawfords may be the way to go? I cant believe you lost power on the dyno. Since you picked up another 2mph in the 1/4 you were obviously making more power. Guessing they may have made some adjustments (maybe calibration?) to the dyno that affected over all output. Most people say that the Dyno is simply a tuning tool and not to worry about the numbers but rather the track performance. You obviously got better track numbers and also said yourself that the car felt better so im sure you gained power. Too bad you couldn't have dynoed back to back on the same day with the two sets of HFCs.
Sharif (FORGED) recommended the Random Tech's. These are pretty close in price to the Crawfords, have you heard anything good or bad between them? Another recommendation by a forum member was the FI & HopUP racing HFCs. Any thoughts are much appreciated.
Aubrey
Thread
Thread Starter
Forum
Replies
Last Post
HeyAsianKid
Intake & Exhaust
3
10-07-2015 01:55 PM
AuAltima3.5
Engine - Exhaust
1
09-20-2015 11:11 AM
