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View Full Version : the end all EXHAUST PURCHASING QUESTIONS thread



trinydex
02-05-2007, 10:59 PM
this question comes up so much in my personal conversations wtih people this will hopefully be one of those end all threads that people read, instead of one of those end all threads that no one reads.

http://www.socalevo.net/forum/index.php?topic=35420.0 this is a thread with fitment pictures.

http://www.socalevo.net/forum/index.php?topic=35262.0 this is a thread with dyno graphs

http://www.socalevo.net/forum/index.php?topic=35595.0 developing thread with sounds.

now for the meat. remember stuff like this is FOR YOU TO SAVE MONEY. so you don't buy and regret.

exhausts are just pipe, mild steal flanges or not. pipe should be cheap. the only exception should be titanium and maybe vband flanges. buying used is not gonna hurt you unless shit is dented up or broken and holey. with that out of the way, ask your self these questions.

how much do i care about fitment?

how much do i care about power?

how much do i care about weight?

how much do i care about sound?

how much do i care about loudness?

how much do i care about the angled tip fruit launcher look?

do i want to be stealth?

now once you've answered these questions consider this.

GENERAL

exhausts make the most power of all initial bolt on upgrades.

lighter pipe means lighter weight, also means louder in most cases.

CATBACKS

having a quiet exhaust means you need resonators, resonators are heavy. that means having a light and quiet exhaust is almost impossible.

having a quiet exhaust doesn't necessarily mean it won't make power. there are full 3" resonators (perforated is best, louvred is what you'll usually find) that will quiet your exhaust and not pose much restriction (fuck what buschur says). so that means you can have a quiet, powerful exhaust.

oval mufflers quiet better than circular ones, more fiberglass and ceramic is more quiet. once again that means more heavy.

most jdm manufacturers don't make stuff truly 3". do your research here FIRST before you buy and regret.

make sure you buy a catback with the o2 bung in the right place or see test pipe section.

if you want to be stealth you're likely going to have to have something custom made in 3" pipe and resonators with lots of resonators, an oval muffler with a tiny tip and painted black. roadrace engineering will hook you up with their stealth exhaust.

having a light exhaust that makes power will likely give you a titanium fruit launcher made of huge piping and makes noise like something loud.

remember that a cop can pull you over for any reasonably suspicion. this apparently includes having a stock exhaust or stock wing.

DOWNPIPES

there's flex section downpipes and donut gasket downpipes. one has a flex to allow for engine movement and one uses the stock system of donut gasket and spring bolts to allow for movement. and then there's the buschur downpipe that doesn't allow for movement and uses exhuast gasket maker globs.

most downpipes require some installation work arounds to fit. some shatty downpipes can be made to fit without rattles and clanging. even the best downpipe can be setup so wrong that it rattles.

most jdm manufacturers don't make stuff truly 3". do your research here FIRST before you buy and regret.

smaller downpipes will fit easier. the power loss arguement is up to you for decision. you're a big boi, flip a coin.

remember anything before the cat is illegal you lil ricer demon you.

CAT/TESTPIPE

the roadrace engineering rallicat is a resonator with cat shields around it. that means it's heavy (also known as a resonated test pipe).

a cat has a matrix of ceramic inside of it. this means it's heavy. metal matrix cats are a little less heavy as they're less dense (available from uber jdm or chinese made helix). the lightest is a test pipe made from anyone and cheapest from anyone in china, find ones that have o2 bungs already there. lighter than that is titanium test pipe (aspec makes one).

a test pipe typically makes about 10hp, or whatever that percentage is of normal horsepower ratings, over a high flow cat. a high flow cat then makes about the same percentage over a stock cat.

running catless daily will likely make you sick from fumes. this is particularly bad with los angeles traffic as your exhaust lingers around you as you crawl along the highway.

remember that if you get caught without a cat it's bad. but if you don't get towed and impounded on the spot you can just pay the fine and never go to the ref.

Mike W
02-06-2007, 02:29 AM
Lots of mystery on what a resonator is and isnt. Maybe these pics will help. Perforated core resonator on the left, louvered core resonator on the right.

http://www.roadraceengineering.com/parts/tweekerparts/perf-louvered.jpg

It is just a straight through muffler but not much volume for noise eduction. They help though. They are used where there isnt much space.

Mike W

deadpirate
01-25-2008, 08:26 PM
hmmm this helped me...but i still have one question.... your saying test pipes and race cats are pretty much the same?

thanks

mbrickner
01-30-2008, 01:09 AM
The one he refers to here seems to be that way.. Race cat seems like a contradiction. If you are racing, you probably don't have a cat. But a high flow cat is bigger and more flowing (But less performing, or sometimes equal, its a tradeoff with flow usually) than a stock cat.

deadpirate
01-30-2008, 09:38 AM
cool thanks

evo1983
02-16-2008, 03:46 AM
thanks man

xtasy127
12-28-2008, 12:55 PM
The one he refers to here seems to be that way.. Race cat seems like a contradiction. If you are racing, you probably don't have a cat. But a high flow cat is bigger and more flowing (But less performing, or sometimes equal, its a tradeoff with flow usually) than a stock cat.


Yeh. That sounds right. Lol race cars have no cats!

EvolOne
05-21-2009, 07:37 AM
Hi,

I have a question that I've never ever been able to get answered. I have an Evo 8 AVO exhaust laying around the garage -- I know it's not full 3" pipe; it's tapered from 2.75 to 3 towards exit -- but I like it pretty much, good quality and such.

And so I've now had a Evo9 since 06 and NOt been able to get anyone to tell me other than welding up the 02 sensor hole what size bolt fits that sensor hole I want to plug.

No sense pardon pun in buying new exhaust when the old one is pretty nice and good quality.

Course after that I need a reflash or something to get the benefits of the bigger opening and better flow.

Thanks,

Mike W
05-21-2009, 12:02 PM
It is an 18mm thread for the O2 sensor. You can use the drain plug from the transmission.

Mike W

4g63kevin
12-14-2009, 09:51 PM
Great thread!

jtran036
12-29-2016, 06:49 PM
Excellent Thread with great info!