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Discussion Starter #1
having worked on hondas for several years, it was always said that for the best performance of a turbo, the exhaust piping should be 2 3/4 to 3in. for maximize exhaust flow due to running boost. i have noticed that most companies that offer exhaust for the 1.8T make their piping at either 2.25 or 2.5in. doesnt that sort of choke the motor? i would think that any turbo engine would benefit from at least a 2 3/4 piping. do the engines not run well with the bigger exhaust or what? i plan on eventually making 300 horses. with that kind of power im affraid ill damage something from running such a small exhaust. i hope that you guys can help me out here. is 2.5 the norm? or do most people really not add so many horses that it would matter? thanks
 

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For the ko3 turbo, a 2.5 inch exhaust will be fine. You do not want to go any bigger because it might over spool the turbo and causes damage. APR releases a stage 3 upgrade with the t3/t04 turbo and they recommend a 2.5 exhaust.
 

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i believe the largest exhaust available is the GHL 3" cat and turbobacks. I know a bunch of people that are running this exhaust with the stock turbo with no probs, but me thinks it is a little unecesary and expensive...
 

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I have heard of some people with the 3" turbo back GHL hitting limp mode because they overboosted the motor. There are a few ways to solve this:

Get the Overboost solution (a 1.8T guy can chime in with the link, I forgot)

Get a bigger turbo (doesnt spool up as fast as the stock KO3)

Don't buy the 3". Settle for the 2.5", its more than adequate...I personally know 2 guys with the GHL 2.5", and it's awesome.
 

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Discussion Starter #5
whats the factory pipe on the 1.8t? i red someplace it was like 2.25... true? the car is only 3 days old now, but real soon, i wanna run AT least a custom axle back. that is why im trying to get as much info on the exhaust setup as possible. thanx
 

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How loud do you want the exhaust to be? The quietest is Milltek (they sell a complete 2.5" turboback thats awesome, just ask RafCarre12) , and the loudest would have to be GHL (loud, but sounds awesome...you can ask Sully NJ 1.8 about his).

There are some other systems out there, but the 2 mentioned above have been agreed upon on this forum to be the best choices.
 

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Discussion Starter #8
to be totally honest, i dont really have a set price range for an exhaust. the problem i have is that i am not impressed with the looks of any exhaust i have seen so far. sounds weird to say but i think that looks play just as important a part as functionality. i dont like the oval exhaust tips, and the car comes stock with dual aluminum tipped exhaust. i am looking for one tip (decent size) with a torched tip. also, i want my exhaust to be different from what most will have.
 

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There are a bunch of good systems out there but, if you want quiet during normal operating rpms go with milltek. They sound great when you open it up but are pretty tame just cruising.

You will probably want to get a high-flo cat with your downpipe if you're going for 300. You could mate up the stock cat but it'll be much more restrictive.

I'd look into GHL, Milltek, Techtonics Tuning, APR (downpipe probably not catback)


Oh yeah, you can always get a different tip to weld on from autotech or another place. A decent muffler shop can make a custom tip for you.

[ March 07, 2004: Message edited by: Gti20thAEinDE ]
 

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Discussion Starter #11
i have seen a few companies that do make the down pipe/cat combo, and i am interested in those. i have seen them range from the 2.5 to the 3in size. for the time being though, seeing as my car isnt even a week old and im already going to get my hands dirty i think i'll just keep the factory downpipe and cat, and also keep the factory axle back stored in my basement(pollution controlled areas)but have a 2.5in custom made for the axle back. when the time comes, ill order the 3in down pipe/high flow cat combo and that will pretty much take care of my exhaust. i will definately keep you guys posted on the progress of things.
 

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i have the techtonics 2.5 turbo back set up, and i love it. its got a nice growl however not to loud. this system is designed to custom fit your own tip. i left it alone because i like my car to look like a sleeper! i would post a pic but my dumb ass doesnt know how to post pics.
if you are in the northern jersey area i would pick you up for a ride.
 

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Discussion Starter #13
the factory resonator on the 2004 1.8t exhaust is located before the axle back, or after??? i just thought about that, cuz i need to plan accordingly depending on where it sits. thanks.
 

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Hey, i just picked up a 3" Forced Motion exhaust (thanks to Josh
) and I am not really all that worried about overspooling, since I will be running stock software until a go for a full turbo upgrade that can really make use of the 3".

Just want to be sure everyone remembers Forced Motion; their exhausts look great, and I can't wait to install mine later this spring.


[ March 07, 2004: Message edited by: 109 LUVR ]
 

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The factory resonator is located before the rear axle. If you do anything exhaust wise, go cat back, not axle-back. The cat-back eliminates the factory resonator.
 

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i just recently purchased a remus exhaust and i'm having it made into a custom 2.5' catback exhaust. the person at the shop told me that 2.5' is perfect for my car if i'm not upgrading the turbo. plus i've read everywhere that 3' does cause over spooling if u don't have an upgraded turbo.
 

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The overboost solution can be found at boostvalve.com


A good medium is a 3" downpipe mated to a 2.5" catback. This will be enough flow for a large turbo however, it will be quieter than a 3" turboback.

As far as choking the system goes, I know of people running apr's stage III kit with the apr downpipe mated to the 337/20th catback. They are putting down a bit over 300 to the wheels without any problems.
 

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I have a 2.5 inch TT down pipe and remus (VW motorsport) cat back not loud while at low rpms but when i really down on it many of the guys i put up with are shocked to hear and just how fast it is. anyways it is all about looking like a sleeper. My tips look great as well i have never seen i can tell sometimes when they see my exhast they can tell that there is something cooking under the hood.

Hope you enjoy your new car and welcome to the 1.8 turbo family.

I am thinking of a new turbo as well. i will have to wait and see. take care and drive safe out there.
 

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Discussion Starter #19
So mating a 3in down pipe to a 2.5 exhaust is no prob? also mating a 2.5 down pipe to a 2.5 is also not bad? the more i know, the better cause i dont want ungodly loud, but i do want a different look for my jetta. thats why im getting at least a custom axle back made. what about cat requirements. if i put too many horses down, then i run the chance of torchin the material inside the cat rite? IF i kept it stock. as i go up in downpipe size, should i up the cat accordingly? like i stated before, my ultimate goal is have at least 300 horses. you guys are a great help already so keep it up
 

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GHL is loud? I want loud, really really loud, cause theres so many hondas around this area , and I want something as loud . So GHL instead of milltek??? Power is my main concern tho thanxxx
 
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