[tim finnegan]

Will an aftermarket, catless, bellmouth type downpipe cause turbo creep for my 2004 STI? I plan on getting it portuned after it is put on.I have been reading and comparing and talking to people. One guy recommends HKS another Invidia and still another Cobb. Then I was reading about DC sports downpipe and thats where I found out about turbo creep or spiking. It goes on to say that it can be fixed by porting the stock turbo's wastegate or by, buying an EMS. Will a protune take care of this? The only other mods on the car are an SPT intake and SPT cat back exhaust.

[Szumita]

get invidia.

hks downpipe is easily the worst design.

a protune can sometimes eliminate creep, but it is a mechanical issue.

[tim finnegan]

any idea how common turbo creep is?

[Szumita]

pretty common with 2.5 + the vf39. and in cold weather more.

[tim finnegan]

Have you seen the DC sports downpipe and if so what do you think?

[IGoFast1589]

If you want to avoid creep get Cobb's downpipe. The Cobb pipe, catless or catted, tapers down to 2.5 inches which will help combat creep. I have a titek catted 3 inch bellmouth and I creep like a b**** during the winter.

[wantsti118]

to add to this topic.. if i get an invidia 3" catted dp and 3" turbo back exhaust plus the cobb ap stage 2 will i get boost creep? i want to avoid this a much as possible. also could even really notice the difference from a 2.5" dp as to a 3" dp? just tryin to do my homework before i buy

[IGoFast1589]

Originally Posted by wantsti118

to add to this topic.. if i get an invidia 3" catted dp and 3" turbo back exhaust plus the cobb ap stage 2 will i get boost creep? i want to avoid this a much as possible. also could even really notice the difference from a 2.5" dp as to a 3" dp? just tryin to do my homework before i buy

Sure, I understand. First off, how far do you plan on going with your engine modifications? A "turboback" exhaust is a catback and a downpipe, just to let you know. If your goal is to avoid creep as much as possible and your future does not include upgrading your turbo, then I would say get cobb's downpipe. If you ARE going to upgrade your turbo in the future, go with a 3 inch because otherwise it may bottle neck in your system. I doubt you would be able to notice any difference between a 2.5 and a 3 inch downpipe at just stage 2.

Do NOT get a downpipe without getting some form of engine management.

[FlyingPerformance]

You can never be totally sure you wont get boost creep with the VF39(even with a stock downpipe). Boost creep is NOT a tuning problem, it is a MECHANICAL issue. The best way(also the most expensive) is to get an EWG setup, viola no more boost creep. Another way to combat it is to port the wastegate on the stock turbo(however you may still get small amounts of creep because you can only open the hole up so much). Another way to combat it is to get a catted down pipe, the slightly added back pressure will help fight boost creep. I know alot of people and have alot of customers running full catless(myself included) who have never had creep. Some do it, others dont, not really a way to predict it. No matter what downpipe you get, you need to get EM on there at the same time(you also have to have EM to be able to get a pro-tune).

P.S. Invidia is what I would go with(I run a V3 catless on mine right now).

[wantsti118]

[quote=FlyingPerformance;1922889]You can never be totally sure you wont get boost creep with the VF39(even with a stock downpipe). Boost creep is NOT a tuning problem, it is a MECHANICAL issue. The best way(also the most expensive) is to get an EWG setup, viola no more boost creep. Another way to combat it is to port the wastegate on the stock turbo(however you may still get small amounts of creep because you can only open the hole up so much). Another way to combat it is to get a catted down pipe, the slightly added back pressure will help fight boost creep. I know alot of people and have alot of customers running full catless(myself included) who have never had creep. Some do it, others dont, not really a way to predict it. No matter what downpipe you get, you need to get EM on there at the same time(you also have to have EM to be able to get a pro-tune).

P.S. Invidia is what I would go with(I run a V3 catless on mine right now).[/quot


i dont plan on upgrading the turbo so should i still get the full 3" exhaust? or is the cobb tbe fine? as i do plan on getting the cobb ap.

[SirMattieP]

Originally Posted by FlyingPerformance

You can never be totally sure you wont get boost creep with the VF39(even with a stock downpipe). Boost creep is NOT a tuning problem, it is a MECHANICAL issue. The best way(also the most expensive) is to get an EWG setup, viola no more boost creep. Another way to combat it is to port the wastegate on the stock turbo(however you may still get small amounts of creep because you can only open the hole up so much). Another way to combat it is to get a catted down pipe, the slightly added back pressure will help fight boost creep. I know alot of people and have alot of customers running full catless(myself included) who have never had creep. Some do it, others dont, not really a way to predict it. No matter what downpipe you get, you need to get EM on there at the same time(you also have to have EM to be able to get a pro-tune).

P.S. Invidia is what I would go with(I run a V3 catless on mine right now).

To add to this, does porting the turbo in order to try eleminate boost creek also add HP or TQ? And how much does this cost.

If you do on or the other, do you have to do them all? Ex: If i upgrade the EWG do i have to port the turbo?

[FlyingPerformance]

Originally Posted by wantsti118

i dont plan on upgrading the turbo so should i still get the full 3" exhaust? or is the cobb tbe fine? as i do plan on getting the cobb ap.

Get what exhaust sounds good to you. Dont buy something because you are going to buy an AP. I personally would get a full 3". You could get an invidia V3 downpipe and pretty much what ever catback that sounds good to you. Dont necessarily get stuck on brands.

[FlyingPerformance]

Originally Posted by SirMattieP

To add to this, does porting the turbo in order to try eleminate boost creek also add HP or TQ? And how much does this cost.

If you do on or the other, do you have to do them all? Ex: If i upgrade the EWG do i have to port the turbo?

Porting the turbo(we port the whole thing) can add HP and TQ by allowing the turbo to spool up a bit faster and hold boost better to redline. Porting just the WG, will not add HP or TQ. If you go to an EWG setup then you do not have to port the wastegate in the turbo because you do not use it anymore. You could still benefit from having the rest of the turbo ported though in that situation. Check out my thread for more info and pricing on the turbo porting.
No-Cut BCS, Cobb AP's, Meth Kits, Downpipes, Exhausts, Pistons, Walbro, Porting Work

[wantsti118]

Originally Posted by FlyingPerformance

Get what exhaust sounds good to you. Dont buy something because you are going to buy an AP. I personally would get a full 3". You could get an invidia V3 downpipe and pretty much what ever catback that sounds good to you. Dont necessarily get stuck on brands.

not really stuck on a brand. but from what ive read invidia has a quality product and they are 5 miles from my work. i talked to them the other day and they said i could buy from them direct. then i was reading on the cobb site that if the exhaust relieves too much pressure that is when boost creep happens. therefore i thought that if the invidia system is too big maybe better to get a 2.5" dp such as the cobb system.

[FlyingPerformance]

well the cobb is a 3" until about 3 or 4 inches from where the downpipe mates to the catback, then is tapers to 2.5 inches to make it compatible with the stock catback. If you go with the cobb catback it starts at 2.5" to be compatible with the stock(or cobb) downpipe and then expands to 3". So in reality you dont have that large of a restriction. If you are worried about boost creap or spikes, go with a 3" catted down pipe and what ever catback you want. I see you are in so-cal, definitely go with a catted down pipe to try to appease the smog police out there.