I need a quiet exhaust system 2.5-2.75"

[johnmk]

Hello folks,

I'm having the ptuning turbo kit (w/ GTX2867R) installed in a few weeks, and need to figure out what to do about the exhaust. I'm concerned about noise, inside and outside of the vehicle, as I drive in a lot of neighborhoods where excess noise would not go over well. I'm also not a fan of needless noise myself, nor are my passengers. My goal is a sleeper vehicle with a modest boost to power.

What I'm reading seems to indicate that the larger the exhaust diameter, the louder the exhaust. Also, since my turbo goals are no higher than 300 horsepower, I don't see the need for a 3" (76mm) exhaust. The sweet spot appears to be around 2.5" (63mm). I think 2.75" (70mm) would be tolerable as well. The stock exhaust being, if I read elsewhere correctly, 2.25" (57mm). I'm not 100% sure that's right though but I can't imagine it being any higher than 2.25". These metric conversions appear quite odd to me, by the way, since I would think the car's specs would be conceived in metric. Why would a non-US car company bother with such odd values as 57mm for an exhaust, when 55mm or 60mm are cleaner values? I wonder if the stock exhaust is really 55mm (2.165"), but anyway, I digress quite unnecessarily here. :-)

The ptuning turbo kit dumps the wastegate into the exhaust, by the way. I'm not sure if that's relevant to my central question in this thread, but it could be if a small diameter exhaust system restricts exhaust flow at a bad time -- I don't know if that's a concern, or not.

I'm considering the Invidia Q300 cat-back exhaust, but diameter appears slightly to the low side of my goal (2.5 being ideal, I think). At only 2.36"(60mm), it doesn't appear to be that much of an upgrade from stock (55mm), though 60^2/55^2 = 1.19. So Q300 has almost 20% more cross-sectional area and should flow at least a bit more air than stock. The Q300 being cat-back, how would I mate it with the ptuning turbo kit components?

Is there something a bit roomier than the Q300 that's also quiet and can be mated with the ptuning turbo kit? I guess anything I get will probably need to have a suitcase-style muffler.

Here's the exhaust system that ptuning have designed for use with their kit.

http://www.ptuning.com/subdir/itemde...&ModelDesc=BRZ

It looks top-notch, but IMO the emphasis appears to be on performance and not noise-suppression. Those mufflers seem awfully small. Is size a fair way to predict muffler performance, in general?

Anyway, please folks. Help me out! There are a dizzying array of options out there and I must decide soon, or my install schedule has to slip.

Thank you so much for your time folks.

-John

[Docmattic]

i know the blitz nur spec is queit

[Ashikabi]

Look at ft86speedfactory, they will have diameters listed on all their exhausts. I was told the suitcase or other large mufflers are more effective than the tuner style cans. I've listened to many sound clips but due to a variety of recording situations they all sound exactly the same to me. My best advice is to find all the exhausts in your price range with the size pipe you want, make a list, pick one of those. Also, I've heard the stock cat back isn't restrictive so I would imagine anything with a larger pipe(like q300) would be fine for 300hp

[Freddy@PTUNING]

To mate other exhausts to our turbo kit, all you need is this v-band to 2-bolt adapter: http://www.ptuning.com/subdir/itemde...&ModelDesc=BRZ

Another quiet option would be the Perrin 2.5" w/ resonator: http://www.ptuning.com/subdir/itemde...&ModelDesc=BRZ

[johnmk]

Will the Perrin 2.5" w/ resonator definitely flow more air than stock, and by a significant margin?

[MisterSheep]

If you're looking for a 2.5in that's quiet and not invidia q300 go with the Perrin Resonated. They also offer the perrin resonated in a 3in as well.

[tumbla.jr]

Corsa FTW

[Northwest86]

I run a q300 turboed. Works just fine. The front and overpipe ahould be more your concern. The 911s never hear me coming

[mav1178]

Originally Posted by johnmk

My goal is a sleeper vehicle with a modest boost to power.

What I'm reading seems to indicate that the larger the exhaust diameter, the louder the exhaust. Also, since my turbo goals are no higher than 300 horsepower...

Based on that above, you can do 300HP on 60mm mandrel bent piping... i.e. you don't have to limit yourself to 2.5" or whatever. 60mm is perfectly fine for what you want to do.

-alex

[Freddy@PTUNING]

Originally Posted by Northwest86

I run a q300 turboed. Works just fine. The front and overpipe ahould be more your concern. The 911s never hear me coming

The Ptuning turbo kit utilizes the front pipe and over pipe for our turbo kit.

[cwpbrz-ji]

Originally Posted by johnmk

dizzying array of options

I am quite happy with my WORKS Exhale ABM (Axle Back Muffler) Exhaust and do not consider it being ‘too loud’ (muffler audio at provided link).

My BRZ @WORKS ::: http://www.ft86club.com/forums/showp...1&postcount=43 sporting the ABM.

[Kostamojen]

If you truly want "quiet" and not just "less loud" then you can't beat the Legsport muffler plus a resonator in the midpipe:

http://www.ft86club.com/forums/showthread.php?t=83973

Even with headers and a resonator less cat pipe, my legsport muffler is extremely quiet. Reason being it has TWO mufflers in sequence which you can combine with a midpipe resonator for much quietness!

[campy]

Why not just stick with the stock headerback? It's relatively quiet and sounds pretty good with an aftermarket header. I don't think you'll notice any significant power difference between stock and an aftermarket 2.75" exhaust anyway.

Plus the stock exhaust is free lol. You can always buy a different one later.