Borla install and review.
This is a very interesting experiment, Jeff. Thanks for the writeup. I chased drone in several exhausts in my old 300ZX for 2 years before finally settling on an HKS Sport model with larger, non-straight through mufflers. I considered the rsonated x pipe setup you have done as well, but never ended up trying it. The larger HKS mufflers seemed to solve the drone problem and returned some lost low-end torque as well. It's mainly why I have left the G's exhaust alone - I couldn't stand the drone in the 1.5-3k RPM range.
Joined: May 2005
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From: ɐʍ 'ǝlʇʇɐǝs
This is a very interesting experiment, Jeff. Thanks for the writeup. I chased drone in several exhausts in my old 300ZX for 2 years before finally settling on an HKS Sport model with larger, non-straight through mufflers. I considered the rsonated x pipe setup you have done as well, but never ended up trying it. The larger HKS mufflers seemed to solve the drone problem and returned some lost low-end torque as well. It's mainly why I have left the G's exhaust alone - I couldn't stand the drone in the 1.5-3k RPM range.
I suspect the noise cancellation characteristics of the non-staight throughs were why you choose them. Thanks for the comments and your experiences about combating drone via the mufflers. I to was thinking of replacing the muffler but although it most likely would have netted less drone, I wasn't sure about the performance gains. So I decided to take a chance at hitting two birds with one stone. For the most part, I did it. Performance in the terms of torque increases is much improved and the drone is definately reduced quite a bit. To the point where I'm happy with it. I suspect this exhuast is now one of the more quiet and torquey dual exhausts out there. Hard to tell though as I've haven't had the chance to hear either of the two Stillens or the Fast Intentions units. (FI uses the same magnaflow resonated X in their system)
Last edited by Jeff92se; Apr 24, 2009 at 01:41 PM.
I wouldn't do it. I think it will hurt exhaust velocity and kill low rpm power. I specifically remember reading in SCC magazine a few years back about a VR6 VW drag car that had a single 3" exhaust and the tuner took it down to 2.5" and saw a gain of about 15whp because of the improved exhaust velocity. The VR6 was stoked to 3.2 liters and was making about 325whp NA.
Dave is right though. I wouldn't run anything larger than 2½" for a single pipe on a VQ35. There just isn't enough exhaust to pull strong pulses, especially if you're looking to do an X-pipe. Run dual 2¼" and you'll have healthier mid range with some extra breathing room up top for higher revs.
Joined: May 2005
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From: ɐʍ 'ǝlʇʇɐǝs
Motordyne seems to like the bigger exhausts but he does mention his exhaust are "track ready". I assume he means a bias towards higher hp numbers up top vs low midrange.
When doing a casual comparision to Dave's setup, Dave reports a loss of power right at 6,200 rpm. If I sit at that range or rev SLOWLY up to that rpm, I can feel a VERY, VERY slight loss of power there. But I have to creep to it to notice. Normally, if I'm not careful, I'll blast right though that rpm range and clang into the rev limiter. Because it's still pulling pretty hard.
So as far as I can tell, my dual 2.25" system seems to give me great low/awesome mid and good top end. (with the X pipe addition that gave back the low end)
When doing a casual comparision to Dave's setup, Dave reports a loss of power right at 6,200 rpm. If I sit at that range or rev SLOWLY up to that rpm, I can feel a VERY, VERY slight loss of power there. But I have to creep to it to notice. Normally, if I'm not careful, I'll blast right though that rpm range and clang into the rev limiter. Because it's still pulling pretty hard.
So as far as I can tell, my dual 2.25" system seems to give me great low/awesome mid and good top end. (with the X pipe addition that gave back the low end)
Joined: May 2005
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From: ɐʍ 'ǝlʇʇɐǝs
Tony's research on diff dia primaries as it relates to his XYZ Y pipe: He's answering a question of why his new Y pipe lost a touch of hp/torque in the very low rpm range. It confirms my thoughts about his product direction.
Everything he says is interesting
Everything he says is interesting
That is to be expected. The XYZ pipe has larger diameter primaries than the stock Y pipe. Its a trade, but overall its a trade well worth doing.
In development, I also tested a 2.25" version of the XYZ pipe. It had a little more TQ in the 1500-3000 RPM range but then it lost about 2-3 HP over the rest of the curve above ~3500 RPM. 2.25" wasn't a good trade.
2.5" primaries provided the best overall results.
In development, I also tested a 2.25" version of the XYZ pipe. It had a little more TQ in the 1500-3000 RPM range but then it lost about 2-3 HP over the rest of the curve above ~3500 RPM. 2.25" wasn't a good trade.
2.5" primaries provided the best overall results.
When doing a casual comparision to Dave's setup, Dave reports a loss of power right at 6,200 rpm. If I sit at that range or rev SLOWLY up to that rpm, I can feel a VERY, VERY slight loss of power there. But I have to creep to it to notice. Normally, if I'm not careful, I'll blast right though that rpm range and clang into the rev limiter. Because it's still pulling pretty hard.
Guess I'd better get on that, eh? So many steps from my vidcam to YouTube or whatever though, and I won't post a crappy Blackberry clip. Maybe this weekend.
Joined: May 2005
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From: ɐʍ 'ǝlʇʇɐǝs
Don't mind me, I'm just archiving more of Tony's comments:
No. Single or dual doesn't make a difference if they are merged correctly. The number of flow paths after the merge point doesn't make a difference if its 1, 2, 3 flow paths or even if its fully open.
The first 2 feet of the primaries is the reactive part of the exhaust system. It is what determines the power curve slope angle.
Beyond 2 feet, the only thing that matters is the flow resistance. IE how free flowing it is. And flow resistance should be minimized to any practical extent possible.
The first 2 feet of the primaries is the reactive part of the exhaust system. It is what determines the power curve slope angle.
Beyond 2 feet, the only thing that matters is the flow resistance. IE how free flowing it is. And flow resistance should be minimized to any practical extent possible.
Joined: May 2005
Posts: 37,810
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From: ɐʍ 'ǝlʇʇɐǝs
Okay, okay.
Install wasn't too difficult, but would have taken less time had I bitten the bullet and dropped the right side of the sway bar to begin with instead of trying to wiggle the right-side pipe through. Oh well.
Stillen Gen 2 is a true dual system, comes off the cats into an x-pipe (non-resonated, I wish it were), then twin resonators and two pipes back to the 2-in 2-out muffler. All 2.5" stainless steel with polished muffler and tips (looks tasty, you won't mistake those tips for stock).
So when I took it down off the jackstands and started it up, I kinda went 'uh-oh', but then it came off high idle and quieted down a bit. Out for a drive, I noticed a fair bit of sound in the cabin of the car. I had the wife do a drive-by and from the outside it sounds SWEET!!! Not quite the coupe howl I was lookin for, more throaty and absolutely no rasp (which I hate). Unfortunately, I don't spend much time outside the car, so really that nice sound is just for other people.
I imagine that I can feel the extra power, so as a performance mod it's well worthwhile, I'm just still deciding whether or not I can live with the intrusiveness of the interior noise. That's why I have a WTB in the Canucka section for an 05 sedan middy, like to try out that setup.
I've considered installing a resonated X-pipe and/or different resonators (like Vibrant) but I don't want to spend a few hundred more and still not be able to live with it.
I also want to truly hear it from the outside on takeoff and at full song, so maybe I'll do a video this weekend.
Install wasn't too difficult, but would have taken less time had I bitten the bullet and dropped the right side of the sway bar to begin with instead of trying to wiggle the right-side pipe through. Oh well.
Stillen Gen 2 is a true dual system, comes off the cats into an x-pipe (non-resonated, I wish it were), then twin resonators and two pipes back to the 2-in 2-out muffler. All 2.5" stainless steel with polished muffler and tips (looks tasty, you won't mistake those tips for stock).
So when I took it down off the jackstands and started it up, I kinda went 'uh-oh', but then it came off high idle and quieted down a bit. Out for a drive, I noticed a fair bit of sound in the cabin of the car. I had the wife do a drive-by and from the outside it sounds SWEET!!! Not quite the coupe howl I was lookin for, more throaty and absolutely no rasp (which I hate). Unfortunately, I don't spend much time outside the car, so really that nice sound is just for other people.
I imagine that I can feel the extra power, so as a performance mod it's well worthwhile, I'm just still deciding whether or not I can live with the intrusiveness of the interior noise. That's why I have a WTB in the Canucka section for an 05 sedan middy, like to try out that setup.
I've considered installing a resonated X-pipe and/or different resonators (like Vibrant) but I don't want to spend a few hundred more and still not be able to live with it.
I also want to truly hear it from the outside on takeoff and at full song, so maybe I'll do a video this weekend.
The drone is in the 1500-2500 range, as others have experienced. If I tach it up to 3k or so it just sounds wicked. I revved it a few times for my friend (he's 40 and a VW driver) and he nearly creamed.