How much interest do people really have in a quiet high-flow exhaust?

[socalsleeper]

Sounds like someone has done his homework. I think that you have made a few great points and that is the questions that any one trying to develop an exhaust system to bring to market should ask.

Most of us don't have the time, knowledge, or resources to develop the type of system you are talking about.

But if a company wants consumer feedback for the next product, an open discussion like this is a good start.

[TRSCobra]

BlackGT any pics of exhaust systems you've built? Whose components do you use?

[BlackGT]

BlackGT any pics of exhaust systems you've built? Whose components do you use?

 

I don't usually take pictures unless I have a special reason, sorry. I'm more of a function over form kind of person. I did find a picture of the dual-cat setup I have on my car now, it includes a 3" attachment to the downpipe, dual 100 cpi cats, and a Magnaflow muffler (used as a resonator - an absorber).

 

As for whose components I use - it varies. I use Dynomax mandrel bends, and usually Magnaflow for absorbers. I have not found any commercially available muffler that works well in our cars, they are all simply too small (not enough volume) to effectively attenuate the low frequency. the stocker does a decent job of attenuating the low freq because it has the big volume and small pipe size to do that, but they have too much back pressure (measured 6psi peak contribution just from mufflers). So I build my own mufflers. 304 Stainless plate (waterjet cut) and stainless tube, tig welded together.

 

Jeremy

[BlackGT]

I would be interested in something even quieter than the stock setup.

 

Aquaflight

 

Do you want a quieter car OR a quieter exhaust? For a stock LGT, there are other contributions other than exhaust to overall noise that make our cars seem loud: Road noise, wind noise, intake noise. Making the exhaust quieter (if you are stock) will not help bring down the overall noise much at all. If there are problem areas (speeds, rpm's), then you can address those independently.

 

Jeremy

[gil_ong]

Update images!

 

http://www.avoturboworld.com/images/stories/2011/leg_midpipe/05leg_midpipe_001.jpg

 

Regards,

 

Paul Hansen

http://www.avoturboworld.com

http://www.facebook.com/avoturboworld

 

showed my wife this last night.

 

"why does a few pieces of bent pipes cost so much?"

 

LOL. have to agree to a point.

[TRSCobra]

I don't usually take pictures unless I have a special reason, sorry. I'm more of a function over form kind of person. I did find a picture of the dual-cat setup I have on my car now, it includes a 3" attachment to the downpipe, dual 100 cpi cats, and a Magnaflow muffler (used as a resonator - an absorber).

 

As for whose components I use - it varies. I use Dynomax mandrel bends, and usually Magnaflow for absorbers. I have not found any commercially available muffler that works well in our cars, they are all simply too small (not enough volume) to effectively attenuate the low frequency. the stocker does a decent job of attenuating the low freq because it has the big volume and small pipe size to do that, but they have too much back pressure (measured 6psi peak contribution just from mufflers). So I build my own mufflers. 304 Stainless plate (waterjet cut) and stainless tube, tig welded together.

 

Jeremy

 

 

You have these mufflers on your LGT? Any other mods?

 

After my mods, my stock catback is still a bit loud for my tastes. Well, not really too loud, but it sounds really tinny, like the mufflers can't quite handle the increased noise from my larger turbine and single-catted cobb DP.

[BlackGT]

You have these mufflers on your LGT? Any other mods?

 

After my mods, my stock catback is still a bit loud for my tastes. Well, not really too loud, but it sounds really tinny, like the mufflers can't quite handle the increased noise from my larger turbine and single-catted cobb DP.

 

Yup, mufflers are on it.

 

I have a 20G, K&N intake (built my own quiet airbox for it), Cobb DP, FMIC.

 

"Tinny" sounds like you are hearing high-frequency noise, which can be cut down to some extent with another absorber (glass-packed resonator) added to the system. Do you see the Dodge ram pickups and GM large SUV's with the little resonators (tiny mufflers) right at the end of the exhaust, right before the tip? Those are put there to remove more high-frequency tinnyness. They are most effective at the very end of the exhaust. Our cars don't have the luxury of additional space like a big truck has, but if you could incorporate some sort of glass packing (absorber) in the rear muffler, that would help a lot. If that was you only complaint, here is what I would do:

 

1) Buy some Perforated stainless steel:

http://www.ebay.com/itm/Perforated-347-Stainless-Steel-Sheet-12-x12-/270773447253?pt=LH_DefaultDomain_0&hash=item3f0b5aea55

 

2) Cut a 10"x10" hole in the top of your stock mufflers.

3) Weld the perf steel flat to cover the hole, so essentially you have a perf steel "window" into your muffler

4) Add a layer of stainless steel wool above the perf steel

5) on top of the stainless, add a layer of exhaust silencer absorber (like the kind for packing motorcycle mufflers): http://www.ebay.com/itm/Muffler-Exhaust-Spark-Arrestor-Packing-Repack-Kit-Pro-/130426974200?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item1e5e0daff8

6) Weld a cap over the silencer absorber to seal up the muffler.

 

This may sound extensive and expensive if you don't have a welder or a friend with a welder, but you will keep all the engineered noise control of the stock system, while removing the tinnyness at its most effective point.

 

I found a lot of "air rush" noise at WOT with my stock cat-back after I changed the downpipe to a Cobb catted one (air rush is like saying: "Shhhhhhhh" really loud). Air rush is attributed to large amounts of turbulent flow, my guess is the turbulence is at the Y-pipe, but I have no testing to confirm this. Like you, I also heard a lot more noise in general after the DP change.

 

Jeremy

[TRSCobra]

Thanks for the suggestions! I plan on grabbing a spare set of stock mufflers to mess around with once my house/garage gets finished. Sounds like a good game plan! I've been wondering if two 04-07 STI mufflers would do the job, while increasing flow. Here's a thread on IWSTI that shows them cut open:

 

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/157263-sti-muffler-hacked-modded-pics-inside.html

 

If you look at the 6th pic from the top, it appears to have an absorber section built in right before the tailpipe.

[BlackGT]

Thanks for the suggestions! I plan on grabbing a spare set of stock mufflers to mess around with once my house/garage gets finished. Sounds like a good game plan! I've been wondering if two 04-07 STI mufflers would do the job, while increasing flow. Here's a thread on IWSTI that shows them cut open:

 

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/157263-sti-muffler-hacked-modded-pics-inside.html

 

If you look at the 6th pic from the top, it appears to have an absorber section built in right before the tailpipe.

 

Wow, neat find!!! If you look a the 7th pic, there appears to be some perforated tube on the ID of the resonated tailpipe (all hacked up), and of course a solid OD. I would expect to see some of the absorber material left over or (at least) mentioned from this hack, but I see none. The resonator could be just be extra volume to address a trouble frequency based on tailpipe length...?

 

Our LGT mufflers also have a similar bulge in the tailpipe (inside the muffler), although I have not torn one apart to see if it has some absorber material in it or not.

 

2 STi mufflers could work well, as they have a ton of volume, but there are 2 problems. One, they don't fit. I've tried. I even paid good money to buy a pair and ship them to my house, then cut up the underside of my bumper cover to get them in there. They just won't fit between the rear anti-roll bar and the rear bumper cover...

 

Secondly: Our Legacy's have a different transfer path for atructure-borne and air-borne noise than the Impreza, and we have a different size/shape/stiffness passenger compartment. So, something that might sound great on the Impreza could sound like crap in our cars due to the different structure (and vice-versa). Also, even between Legacies, there will be a sound difference in the sedan and wagon models, and the ones with moonroofs and without. Mine is a 2005 non-limited GT, so I do not have the moonroof, and I've often thought that my roof panel is horribly flexible, possibly amplifying airborne noise in its resonany frequency. Of course, it could be reversed and the moonroof car, with its additional mass hanging off the roof panel, is a problem. I just don't know the answer as I just have not got around to measuring it.

 

Jeremy

[TRSCobra]

2 STi mufflers could work well, as they have a ton of volume, but there are 2 problems. One, they don't fit. I've tried. I even paid good money to buy a pair and ship them to my house, then cut up the underside of my bumper cover to get them in there. They just won't fit between the rear anti-roll bar and the rear bumper cover...

 

Secondly: Our Legacy's have a different transfer path for atructure-borne and air-borne noise than the Impreza, and we have a different size/shape/stiffness passenger compartment. So, something that might sound great on the Impreza could sound like crap in our cars due to the different structure (and vice-versa). Also, even between Legacies, there will be a sound difference in the sedan and wagon models, and the ones with moonroofs and without. Mine is a 2005 non-limited GT, so I do not have the moonroof, and I've often thought that my roof panel is horribly flexible, possibly amplifying airborne noise in its resonany frequency. Of course, it could be reversed and the moonroof car, with its additional mass hanging off the roof panel, is a problem. I just don't know the answer as I just have not got around to measuring it.

 

Jeremy

 

Well there goes any hope I had for some STi mufflers!

 

I'm not overly concerned with how it sounds in the car as much as how loud it is outside. My stock mufflers sound nice and quiet inside, but too tinny, like the old chevy corsica my mom used to have with the cat punched out.

 

I'm waiting to hear the new TurboXS mufflers before I do anything.

[BAC5.2]

I can get some sound clips on a WRX, but they won't represent the Legacy sound. The Legacy mufflers will be quieter, because they'll have more volume and different internal paths. I'd expect them to be quieter than the Invidia exhaust, and we will modify the kit as needed to kill drone inside the car (wagons especially).

[BlackGT]

I can get some sound clips on a WRX, but they won't represent the Legacy sound. The Legacy mufflers will be quieter, because they'll have more volume and different internal paths. I'd expect them to be quieter than the Invidia exhaust, and we will modify the kit as needed to kill drone inside the car (wagons especially).

 

I'm glad to hear that you have the ability to modify the kit as needed to kill the drone inside the car. I'm guessing that its going to be hard to please everybody though, some people will think it is too quiet, some will think it is too loud...

 

Good luck! If you can, please share with us what you are able to modify on the exhaust kit in order to kill the drone.

 

thanks,

Jeremy

[BAC5.2]

It's easy to modify when you are doing primary design with the manufacturer!

[vet]

BlackGT,

 

Is there anything worthwhile to be gained (less noise) by wrapping exhaust pieces? If so, can you give some details/ideas?

[frank_ster]

on mine just adding 6" long tail pipes to the bare mufflers made it quieter.

[boxkita]

I can get some sound clips on a WRX, but they won't represent the Legacy sound. The Legacy mufflers will be quieter, because they'll have more volume and different internal paths. I'd expect them to be quieter than the Invidia exhaust, and we will modify the kit as needed to kill drone inside the car (wagons especially).

 

Do you have an eta for this system? I'm looking for a quiet, high flow system to be installed late Dec/early Jan. Preferably same or (very) slightly louder than stock.

 

If you need a wagon to test fit, I'll volunteer. :-)

[TRSCobra]

Do you have an eta for this system? I'm looking for a quiet, high flow system to be installed late Dec/early Jan. Preferably same or (very) slightly louder than stock.

 

If you need a wagon to test fit, I'll volunteer. :-)

 

He's got his own thread about it here:

http://legacygt.com/forums/showthread.php/turboxs-midpipe-y-pipe-development-168839.html

 

IIRC, he's been pretty busy with work lately, so updates on this exhaust have slowed significantly. I hope the development hasn't stopped! And since he's located in Maryland, and has a wagon himself, I doubt he really needs any wagon volunteers.

[csperformance]

Has anybody ever used this exahust http://www.ultimate-racing.com/xcart/product.php?productid=74&cat=55&page=1 ?

 

Just wondering how it sounds. I have a friend who has their exhaust on his S2000 and loves it.

[TRSCobra]

Looks like they just welded up some generic magnaflow mufflers. Without a resonator, I'd be willing to say it's as loud as the Magnaflow CBE. And $300 more expensive...

[frank_ster]

are not magna flow mufflers pretty much a resonator? i'm sure it depends on thier product line but most i have seen are strait through perforated pipe inside what ever oval or round type muffler.