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Can someone please enlighten me on some exhaust system basics. Basically my exhaust is WAY WAY too loud and i need to make it quieter without re-ducing performance. I have a decent mufler and i have been told i can;t go a quiter one there. And my system currently has a resignator and no hotdog.

Im just wanting to know...

What does a Resignator do?

What does a Hotdog do?

Dave

a resinator is best described as a small muffler - ie has baffles that slow the exhaust gases by creating turbulance in one way or another.

A Hotdog (hmmmm...hotdog) does a similar job but is packed with fibreglass to absorb the sound - is straight thru (ie no baffles) when looking thru them.

I have used them on Turbos / NA, and on non-subarus over the years and have always been happy

For your application, go a couple of 'dogs. When if set up right will = quiet exhaust round town or cruising at highway speeds - hate cars that drone - and a good note on WOT, without affecting peformance

sven

Every solid thing known to us has a natural frequency or vibration period .
Often what people think is a noisy exhaust is a rigid exhaust transmitting that low hum/vibration to our mobile boom box (cabin space) .

Firstly does your car have a "soft spot" in its exhaust ie one of those two bolt sprung carbon ring joints or the stainless bellows flex joint with the braided wire outer cover ?
Big diametre exhausts make great "engine steady bars" but you don't have the NVH (noise vibration harshness) qualities of an engine mount if the exhaust is rigid .

Lastly even turbo exhausts don't have to be HUGE . There is a rough rule of thumb with exhaust diametre and horse power , if you can find out how much you have and equate it to the exhaust size used on a NA engine of similar output its a start . If its an EA82 I wouldn't go over 2.25" maximum . The reason being that the std header is so woeful and the std turbine housing outlet so small that theres little if ANYTHING to gain .

aww i think hatchie sounds good the way she is. quiet when cruising around but then snarls like an angry bear when you give it some herbs. but yeah try some hotdogs in there to make it a lil quieter.

an extra hot dog or resonator will do the job for you without affecting flow. any exhaust shop will be able to hook you up

I get a good note a pretty good performance out of a 2in exhaust with a turbo type muffler with 2in and out the noise is good and the ride inside not deafening. With the EJ22 you could probably go a tad larger if you wanted to but i have not ever noticed a gain in power with a bigger exhaust. (seat of pants observation in the drivers seat).

The best setup i have driven had the standard headers cut to form a "Y" and then an aftermarket cat added in behind it then 2in all the way to the single muffler in the usual L series spot.

id call a resonator the same thing as a hotdog(torpedo resonator)

its perhaps more the traditional oval shape, but would be straight through and have dimensions of say-5"by 3" by 16" long for eg.---sounds to me like you have a fully unbaffled system(straight through) and would benefit from a baffled muffler(larger oval of course--normally offset-centre inlets)to get the noise down. this wont effect the power output, may just slighlt alter the peak torque range.

my car has a small 2"cannon and 2 resonators jammed underneath(all straight through) also a catalytic converter of course so its throaty but not annoying.

with bigger pipes---------
wagons always drone in your ear,,,,no catalytic..is always more noisy,,,,,
only turbos need more than 2"(generally-4cyl..)

Hotdogs ftw. I run 2x hotdogs on the STI to reduce the rumble/scream on noise and still have great performance and a great engine note.
I have one placed just after the dump pipe and one before the rear muffler.

Excelent... thanks for the info guys... i currently have a resenator but it has taken a hit. A hot dog style shape makes more sence for offroad. Exhaust guy recons i have a pretty quiet mufler already which made me laugh. So time to add some hot dogs im thinking.

It was just bearable before i added the Supercharger but that has made it sound much much louder. I like being able to have conversations in the car at freeway speeds.

Dave

i reckon the exhaust is AWESOME....lol
she needs more soundproofing frmo the outside me thinks.


hotdog is the same thing as a resonator.
both fibreglass packed thingos.

If you buy a reasonably priced hotdog they come with a very thick outer wall which is perfect for offroad knocks. I brought one about 10 years ago for my L touring wagon and took it off cause it made the noise out the pipe have datto cackle. Anyway i used it on a later project but had to shorten it and it had a side wall of about 2mm