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Thread: what size exhaust for gsi?

  
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    oztek astra's Avatar
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    what size exhaust for gsi?

    I want to get a new exhaust made up for my mk4 gsi, what size exhaust should i be looking at for best power gains? 2.5" 2.75" or 3"? i noticed most ppl go for around 2.5", is there anyone running bigger? i want the lease restrictive for bhp but not sure if 3" will lower the torque? will be a custom stainless system, pre cat, sports cat, and silencers. thanks in advance.

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    jamesmurray's Avatar
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    2.5inch for anything upto 300bhp seems to be the way of most people here.

    jimbo
    ASTRA MK4 GSI TURBO
    WAS CS3 268bhp & 282lb/ft
    NOW CS4 279bhp & 336lb/ft

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    Neilc's Avatar
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    back pressure doesnt matter on turbo cars as the turbo sorts that out.

    The more free flowing the better, if you are spending the money now just go 3" and be done with it
    Insignia CDTI 160
    200bhp DTUK
    2007 Suzuki GSXR for the weekends

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    Scottyboy's Avatar
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    Really depends on what your plans are?

    As James says, 2.5" is the choice for most and is good up to and maybe beyond 300bhp. If you are planning on a high bhp monster, than get yourself a 3" system.

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    Dave Broomfield's Avatar
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    Ive got a blueflame 3ins and it's ace i'll get some pictures up of it later i think blueflame said it would cost about £650 for a full exhaust form the turbo back
    Corsa c turbo

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    oztek astra's Avatar
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    Quote Originally Posted by THE VALET MAN View Post
    Ive got a blueflame 3ins and it's ace i'll get some pictures up of it later i think blueflame said it would cost about £650 for a full exhaust form the turbo back

    yeah pics would be great mate, see what clearance is. is your precat and main cat 3" aswell?

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    Dave Broomfield's Avatar
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    Yes mate 3ins precat and sports cat
    Corsa c turbo

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