Discoveries on the Stillen Sedan Exhaust
#1
11-22-2004, 02:10 PM
Discoveries on the Stillen Sedan Exhaust
Ok, so I went to this highly recommended exhaust shop and here's what was decided:
1) The resonators in there are actually REALLY good.
2) The X-pipe design is ok, it's not the worst x-pipe in the world, but not the best either
3) The muffler itself is a joke
3a) The muffler has dual-inlets into a common collection area, then one large pipe down the muffler element (yes single exhaust) and then one more common collection area into the two tips.
NOTE: It's a crime to call this a full, true dual exhaust system.
Onto options for reducing noise:
1) Replace the X-pipe with a muffler that has a built-in X-pipe, thus, a muffled x-pipe. The one recommended to me was the Magnaflow 12468 2.5" dual in/dual out muffler. There's plenty of space if you chop out the xpipe and adapt this to fit. According to these guys who really know their stuff, there should be no loss in power if it's installed properly, if anything, Magnaflow's Xpipe is a better design and there's possibility for gains. However, chances are the minimal gains would be tarnished by the installation process. Potential minimal loss but nothing really big to worry about.
2) Replace resonators with large 22" resonators.
2a) The original resonators could actulally be removed and installed in the rear section of the exhaust. Quite a bit of piping would have to be redone losing some power due to more restriction in the piping (unless you want to do custom mandrel bent).
3) Replace the muffler with a better one. This is a tough sale because everyone loves the looks of the Stillen and its tips.
4) Any combination of the above.
4a) That's the beauty is you can do just one of the options and if you decide you want more quietness you can choose another.
5) The simple fix to the problem, but also the worst. Unfortunately, this is what I was forced to do because we couldn't locate the Magnaflow part number needed in option 1. We did order it, so this fix is temporary for the next couple of weeks until I get back to get option 1 done.
Basically, we plugged the left tip with a plug. You can't see it unless you look directly into the tip (with a flashlight). I was skeptical at first, but the exhaust shop guys said it should help a bit and get you through your road trip without the annoying sound. Again, I was skeptical, especially since the muffler isn't a dual muffler. It took about 3 minutes to tack weld the restrictor plate into the tip and after starting up my jaw dropped. The noise literally cut in half; this is how it SHOULD sound. It's very mature, very smooth, and much quieter (inside and out), but you can still tell it's one helluva badazz car. It's about the same volume as the 350z now (stock), maybe a tad louder.
Anyways, the power curve did take a hit non this. By my estimations, the Stillen exhaust did add a real ~15whp to the car. With this restrictor plate in, I feel I lost about 10 of that 15whp. I guess this may be more comparable to the Borla now.
Next week when I return from my road trip, they will untack the restrictor and install the new x-pipe. It should be awesome then, can't wait. I'll provide a detailed write-up then and will provide pictures.
I'm pretty excited, at least with the restrictor plate I made the Stillen exhaust tolerable!!!!
04 6MT Sedan - Z Tube, K&N Drop-In, 04 Z Suspension, 18x8 / 18x9 HP EVO Rims
1) The resonators in there are actually REALLY good.
2) The X-pipe design is ok, it's not the worst x-pipe in the world, but not the best either
3) The muffler itself is a joke
3a) The muffler has dual-inlets into a common collection area, then one large pipe down the muffler element (yes single exhaust) and then one more common collection area into the two tips.
NOTE: It's a crime to call this a full, true dual exhaust system.
Onto options for reducing noise:
1) Replace the X-pipe with a muffler that has a built-in X-pipe, thus, a muffled x-pipe. The one recommended to me was the Magnaflow 12468 2.5" dual in/dual out muffler. There's plenty of space if you chop out the xpipe and adapt this to fit. According to these guys who really know their stuff, there should be no loss in power if it's installed properly, if anything, Magnaflow's Xpipe is a better design and there's possibility for gains. However, chances are the minimal gains would be tarnished by the installation process. Potential minimal loss but nothing really big to worry about.
2) Replace resonators with large 22" resonators.
2a) The original resonators could actulally be removed and installed in the rear section of the exhaust. Quite a bit of piping would have to be redone losing some power due to more restriction in the piping (unless you want to do custom mandrel bent).
3) Replace the muffler with a better one. This is a tough sale because everyone loves the looks of the Stillen and its tips.
4) Any combination of the above.
4a) That's the beauty is you can do just one of the options and if you decide you want more quietness you can choose another.
5) The simple fix to the problem, but also the worst. Unfortunately, this is what I was forced to do because we couldn't locate the Magnaflow part number needed in option 1. We did order it, so this fix is temporary for the next couple of weeks until I get back to get option 1 done.
Basically, we plugged the left tip with a plug. You can't see it unless you look directly into the tip (with a flashlight). I was skeptical at first, but the exhaust shop guys said it should help a bit and get you through your road trip without the annoying sound. Again, I was skeptical, especially since the muffler isn't a dual muffler. It took about 3 minutes to tack weld the restrictor plate into the tip and after starting up my jaw dropped. The noise literally cut in half; this is how it SHOULD sound. It's very mature, very smooth, and much quieter (inside and out), but you can still tell it's one helluva badazz car. It's about the same volume as the 350z now (stock), maybe a tad louder.
Anyways, the power curve did take a hit non this. By my estimations, the Stillen exhaust did add a real ~15whp to the car. With this restrictor plate in, I feel I lost about 10 of that 15whp. I guess this may be more comparable to the Borla now.
Next week when I return from my road trip, they will untack the restrictor and install the new x-pipe. It should be awesome then, can't wait. I'll provide a detailed write-up then and will provide pictures.
I'm pretty excited, at least with the restrictor plate I made the Stillen exhaust tolerable!!!!
04 6MT Sedan - Z Tube, K&N Drop-In, 04 Z Suspension, 18x8 / 18x9 HP EVO Rims
#3
11-23-2004, 04:20 PM
Re: Discoveries on the Stillen Sedan Exhaust
if you're gonan do all that, you might as well make a custom exhaust rather than spend a grand on the stillen and then change everything out. but i did want to change out that damn muffler though. i wanted to put in 2 canister ones, but then i was afraid it would sound like one of those damn civics. oh well.
G35s6mt/TSecu/350Z Springs&Struts/K&Nfilter+Z-tube/StillenDualExhaust /6WireGroundKit/KinetixHighFlow
G35s6mt/TSecu/350Z Springs&Struts/K&Nfilter+Z-tube/StillenDualExhaust /6WireGroundKit/KinetixHighFlow
#4
11-23-2004, 05:28 PM
#5
12-01-2004, 08:22 PM
Well today I put in that Magnaflow muffler. It worked out really well, it fit in nearly perfectly without needing to add any piping. That's good because I didn't have to insert any crush-bent piping or make any mandrel piping. The stillen x-pipe was removed so it can be welded right back on with little effort.
Here's a picture:
Verdict - Sound:
A lot quieter. When you rev it in idle it sounds real smooth and clean. It's much quieter, I can't illustrate how much quieter it is but it's no longer embarrassingly loud like it was before. It's probably about as loud as a stock Corvette or M3 is. It's quieter throughout the entire rev band but you can still faintly hear it most of the time. Closer to redline it gets washed out by the engine noise but you can still barely hear it behind the engine noise. It does drone about at 2500 RPM but then stops at about 3000. It's a significant improvement in being able to live with it, it's not embarrassing anymore, and it's still fun to hear.
Verdict Perfomance:
Performance seems to be pretty close to how it was before, I have no good way of measuring it but I noticed a power drop when I put that restrictor in and now power is up again. I'd say the power is only very slightly depreciated if anything at all. Still massive gains over stock.
Conclusion:
Definitely turned the stillen exhaust from an impossible to live with exhaust into a respectable, worthy modification. I only wish I could delete the drone at around 2500 RPM; I think I'm going to try the Hydrazine fix to help with that. It's important to note, it's still significantly quieter at 2500 RPM then it was before.
The end all conclusion is a Stillen exhaust with the volume cut in half. I don't have a Borla so I don't know how it compares in sound and performance, but for those worried about the volume of the Stillen, definitely consider this an option.
Here's a picture:
Verdict - Sound:
A lot quieter. When you rev it in idle it sounds real smooth and clean. It's much quieter, I can't illustrate how much quieter it is but it's no longer embarrassingly loud like it was before. It's probably about as loud as a stock Corvette or M3 is. It's quieter throughout the entire rev band but you can still faintly hear it most of the time. Closer to redline it gets washed out by the engine noise but you can still barely hear it behind the engine noise. It does drone about at 2500 RPM but then stops at about 3000. It's a significant improvement in being able to live with it, it's not embarrassing anymore, and it's still fun to hear.
Verdict Perfomance:
Performance seems to be pretty close to how it was before, I have no good way of measuring it but I noticed a power drop when I put that restrictor in and now power is up again. I'd say the power is only very slightly depreciated if anything at all. Still massive gains over stock.
Conclusion:
Definitely turned the stillen exhaust from an impossible to live with exhaust into a respectable, worthy modification. I only wish I could delete the drone at around 2500 RPM; I think I'm going to try the Hydrazine fix to help with that. It's important to note, it's still significantly quieter at 2500 RPM then it was before.
The end all conclusion is a Stillen exhaust with the volume cut in half. I don't have a Borla so I don't know how it compares in sound and performance, but for those worried about the volume of the Stillen, definitely consider this an option.
#6
12-02-2004, 10:53 PM
Brian,
I think it's cool you did that. I know Stillen says they put allot of effort into optimizing the X pipe but at least you traded it for something tangible.
You can be sure that the dual large diameter piping of the Stillen system will significantly reduce back pressure and even if you lost any gains made by the x pipe, you are still getting gains from a system that is much better than stock. If you come to LA let me know. I would like to hear it.
Right now I am switching out the Stillen muffler for Magnaflow mufflers. Even if it doesn't change the sound much I know it will reduce back pressure by nearly 3 psi. A reduction like this can only help HP.
I think it's cool you did that. I know Stillen says they put allot of effort into optimizing the X pipe but at least you traded it for something tangible.
You can be sure that the dual large diameter piping of the Stillen system will significantly reduce back pressure and even if you lost any gains made by the x pipe, you are still getting gains from a system that is much better than stock. If you come to LA let me know. I would like to hear it.
Right now I am switching out the Stillen muffler for Magnaflow mufflers. Even if it doesn't change the sound much I know it will reduce back pressure by nearly 3 psi. A reduction like this can only help HP.
#7
12-03-2004, 01:32 PM
Originally Posted by Hydrazine
Brian,
I think it's cool you did that. I know Stillen says they put allot of effort into optimizing the X pipe but at least you traded it for something tangible.
You can be sure that the dual large diameter piping of the Stillen system will significantly reduce back pressure and even if you lost any gains made by the x pipe, you are still getting gains from a system that is much better than stock. If you come to LA let me know. I would like to hear it.
Right now I am switching out the Stillen muffler for Magnaflow mufflers. Even if it doesn't change the sound much I know it will reduce back pressure by nearly 3 psi. A reduction like this can only help HP.
I think it's cool you did that. I know Stillen says they put allot of effort into optimizing the X pipe but at least you traded it for something tangible.
You can be sure that the dual large diameter piping of the Stillen system will significantly reduce back pressure and even if you lost any gains made by the x pipe, you are still getting gains from a system that is much better than stock. If you come to LA let me know. I would like to hear it.
Right now I am switching out the Stillen muffler for Magnaflow mufflers. Even if it doesn't change the sound much I know it will reduce back pressure by nearly 3 psi. A reduction like this can only help HP.
I was in LA last week and I doubt I'll ever drive out there again due to gas prices and the loss of a windshield (and 20 hours of driving is no fun). Do you think your fiberglass cloth mod will help my system lose the slight drone at 2000-2700 RPM?
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