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Discussion Starter #1
so would it it be bad idea... (not considering laws, sound, CEL or anything just hp) to have a straight 3 inch pipe from the turbo all the way back? Because my friends dad owns a muffler shop and he told me he would put a straight pipe all the way back or include a high flow cat from the turbo to the back... i dunno he seemed like he knew what he was talkin bout....
 

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I say go for it!!
But atleast add some highflow mufflers/muffler and maybe a resonator on the midpipe

You dont want to be super loud and run without cats, or your asking for trouble
 

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Def throw a highflow cat in there, but straight pipe rocks, i had it on my c5 corvette and i loved it. it should give you some good gains, but it will be loud and if you want to cut down noise inside the car a good maybe 12" resonator or so. just remember if you are opening up the exhaust you should also open up the intake as well, because you need to compliment parts, if you increase exhaust flow, you will get optimal results if you increase your intake as well (especially since the stock intake is so damn restrictive).
 

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(not considering laws, sound, CEL or anything just hp)
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with those criteria? straight pipe would be ideal and not a bad idea at all except you would need an 02 emulator on 2nd 02 sensor to prevent CEL. or... drop a high flow cat on the down pipe between the two 02 sensors. go single out for less weight and no y-pipe restriction.

Personally i would put at least one straight through muffler and a resonator, if not two. These won't hinder performance at all and will keep the drone out of the cabin.
 

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You can do what you want, but for the car/combo in it's present state a 3" is way overkill. 3" could support close to double the HP this car is making.

What would help is no cats or hi flo cats, no mufflers or single high flow muffler and get rid of the T union. Be aware boost creep will probably become an issue regardless what you do.
 

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You can do what you want, but for the car/combo in it's present state a 3" is way overkill. 3" could support close to double the HP this car is making.

What would help is no cats or hi flo cats, no mufflers or single high flow muffler and get rid of the T union. Be aware boost creep will probably become an issue regardless what you do.
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if you're getting rid of all that stuff, you're running completely new pipe anyway. 3" won't cost that much more than 2.5", and with a turbo, there's no such thing as too big.

Just make sure it's mandrel bent.
 

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if you're getting rid of all that stuff, you're running completely new pipe anyway. 3" won't cost that much more than 2.5", and with a turbo, there's no such thing as too big.

Just make sure it's mandrel bent.
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That is true, but it seems folks think they "need" a 3" when in fact they don't.
 

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That is true, but it seems folks think they "need" a 3" when in fact they don't.
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Some people would call this... "future ready".
 

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dont get me wrong straight pipes r the shit especially on a harley, loud as fuck but a little back pressure is better for performance purposes. a dyno would say the same thing 3" straight is too freed-up.
 

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dont get me wrong straight pipes r the shit especially on a harley, loud as fuck but a little back pressure is better for performance purposes. a dyno would say the same thing 3" straight is too freed-up.
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Wrong..... for a turbo NO pipe would be best.
 

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Most of the comments on this post are far from accurate...

The larger the diameter of the exhaust the higher the power output on a turbocharged vehicle...

And as for killing low end toque, the larger the exhaust the sooner the turbo will spool....

A dyno will prove this...

On most NA vehicles a 2.5" exhaust is good, but on a turbocharged vehicle its a waste of money...
 

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dont get me wrong straight pipes r the shit especially on a harley, loud as fuck but a little back pressure is better for performance purposes. a dyno would say the same thing 3" straight is too freed-up.
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You want exhaust velocity, not backpressure. Too big of a pipe on a N/A vehicle, no exhaust velocity (power loss down low, slight gain up high). Too big of a pipe on a turbo vehicle? No such thing.
 

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Wrong..... for a turbo NO pipe would be best.
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i thought he was sayin he didnt have turbo yet thats how i came about my responce, with turbo the only restriction you need to worry about is the law
 

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Discussion Starter #14
aright thanks alot... i could care less for noise an stuff... louder is better... im juss 18 yrs old anyways so who cares... no image to maintain... but would boost creep be an issue for sure? or just a chance... cuz if i get boost creep... then no way am i doing this....
 

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aright thanks alot... i could care less for noise an stuff... louder is better... im juss 18 yrs old anyways so who cares... no image to maintain... but would boost creep be an issue for sure? or just a chance... cuz if i get boost creep... then no way am i doing this....
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that will depend on how well he fabricates the down pipe.

i thought he was sayin he didnt have turbo yet thats how i came about my responce, with turbo the only restriction you need to worry about is the law
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This is the MPS forum. They come with turbo's. :slap:
 

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Discussion Starter #16
well dj petey i see u have a custom exhasut too... any boost creep? and the guy is not juss sum fool not knowin what he is doing.. i mean he has a turbo audi with a similar set up... sooo... i dunoo...
 

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well if hes a good friend and will do it extremely cheap theres only one way to really tell if your gonna get boost creep. if its cheap i say do it. if it turns out ur geting boost creep. be like "yo dads friend wtf". see if he fixes it. if not then put stocker back on.
 

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well dj petey i see u have a custom exhasut too... any boost creep? and the guy is not juss sum fool not knowin what he is doing.. i mean he has a turbo audi with a similar set up... sooo... i dunoo...
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haven't put in my boost gauge yet but i'm running a stock down pipe so there's very little chance of boost creep right now. I won't do a down pipe till the boost gauge is in.
 

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Boost creep will only happen with a new downpipe...

Most of the time this only occurs if you go completely catless...

The PCM opens the wastegate so much as it is in the high rpm's i don't think creep is going to be much of an issue...

Now the guys with MBC's or EBC's, they might see a slight jump, but even then I have my doubts...
 

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Would boost creap eliminate the need for a boost controller? :D
How much psi does boost creep usually add by removing the cats?
 
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