Quiet Exhaust?

[Gwydre]

I've got a HKS Hi-Power muffler on my 88 which the previous owner put on, and it's got a great loud tone. for me, though, I much prefer a quiet sound, almost unnoticable if you will. I'm looking to replace it, since it's in the garage for a BHG job anyway. I don't know where to go to get the quiet sound I'm look for. Any suggestions would be greatly appreciated.

 

[gofastgeorge]

You probably have to look at an OEM type set-up,
with primary & secondary full fledged mufflers.

 

[Rennat]

or just weld in another straight thru muffler, should tone it down quite a bit.
vibrant sells those "ultra quiet resonators" also which are just about the same thing.

 

[Gwydre]

oh and another question: will quietening the exhaust like this reverse the small efficiency gain that you get out of the louder muffler? I'd prefer not to do so if that's the case.. if that is the case, can I quiet it without the efficiency loss? will the resonator help with that? I'm not too knowledgeable about this.

 

[Rennat]

your talking about such marginal HP and TQ its not worth if...

the Tanabe exhaust has two big mufflers in it which is why its so quiet, but people love it. on the other hand you have the RSR exhaust which is damn near straight as a line and one tiny muffler on the back, but its loud as hell.

if you want a quiet exhaust, dont worry about power, and arent you n/a anyways?

 

[Gwydre]

yeah yeah I'm an N/A but I have plans when I have the cash to go for more power/maybe a n/a-T conversion. need to know a lot more first, however. This one's my daily driver, and I get hassled for the loudness... down the line when I build it up will the quieter exhaust cause me any problems? I don't know why it would but just checking.

 

[CRE]

Add a turbo... that'll quiet it down a fair amount.

I don't recommend straight through resonators which only use a perforated tube and packing as a damper.

If you want to prevent flow restrictions AND quiet things down you need to look into a resonator which uses technology like a Helmholtz resonator to cancel out the noise. They're tuned for specific frequencies outside of which the volume will get louder on a logarithmic scale so you need to find the sweet spot for cruising.

The quietest thing you're going to find would be a baffled resonator coupled with a baffled muffler... but damn they're restrictive.

Aero Exhaust makes such a resonator. I'm planning on getting one (hopefully soon) for my system.

 

[Rennat]

i've been wondering, is it just a mufler? or is it a FULL exhaust from the cat-back?

 

[CRE]

i've been wondering, is it just a mufler? or is it a FULL exhaust from the cat-back?

Could you be more specific? What precisely are you asking about?

 

[Gwydre]

have been looking at the Tanabe medallion touring catback, but can't seem to find one that comes from Tanabe to fit the MKIII. Anyone know where I might be able to find one?

 

[roundfinger]

On a turbo car i was EXTREMELY pleased with the "quiet" factor of the HKS dual tip exhaust for the turbo cars....I like quiet and it was almost too quiet... they make a kit for NA's too.

 

[Gwydre]

Roundfinger you mind giving me a link to that HKS dual tip?

 

[CRE]

Roundfinger - I know you just mentioned that there is a N/A version of the exhaust you liked... this isn't in reference to that, but it should be brought up before someone says that a turbo exhaust will sound the same on a N/A.


One thing a lot of people fail to consider or don't know to begin with is that turbos themselves quiet the exhaust a considerable amount. An exhaust that may be extremely quiet and smooth sounding on a GTE may be terribly loud and raspy on a GE... or worse.

 

[roundfinger]

CRE is 100% correct in that the exhaust on an na to turbo will not sound the same and manufacturers make kits different for NA and turbo for a reason. Sadly sometimes you have to try more than one exhaust if you can't find someone that already has the setup you want to listen to, in person or on youtube. On my old NA i went with a custom setup using a dynomax muffler with a chrome resonator tip and no cat (this was in 1992)...it was WAY TOO LOUD...I had to add a hi flo cat to get it to bearable levels....and it was still loud under WOT

The HKS kits for NA's are https://935motorsports.com/catalog/product_info.php?cPath=79_14_16_31&products_id=240

https://935motorsports.com/catalog/product_info.php?cPath=79_14_16_31&products_id=158

I say you turbo the car Boost is fun.

 

[Gwydre]

my first supra was an 87 turbo so I know where you're coming from... and as I said earlier at some point I'll do the n/a-T conversion but for now I'll see what I can get from my naturally aspirated little 88.

 

[CRE]

MKIII's are NOT common cars and sound clips and streaming videos NEVER sound like the real thing... videos are usually the worst.

I did a lot of research online and found some local owners who were running components I had found an interest in from sound clips online... So, who had all of the various components in all of these cars? BMW owners! The older M3's (and many other BMW's) ran 3 liter inline 6's which sound much closer to what you're going to get with your own setup than anything you'll find online.

Granted I was pretty much already set on a Borla exhaust setup before I met up with anyone with a similar setup on their M3.

No, M3's still don't sounds exactly like our cars, but when you're looking for online clips if you don't keep the type of engine and size in mind you're going to be getting rather confused by the differences in sound as one clip may be a 4 cyl honda and the next a 5 liter V8.