Thread: Would I benefit from a 3" exhaust

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  1. #1 Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    Just like the thread states. Im curious if anyone knows if i would benefit from a 3" exhaust or not with the mods i have listed in my sig over the 2.5" i have now.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  2. #2 Re: Would I benefit from a 3" exhaust 
    GrandPrix Junkie CTKGP09's Avatar
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    how much hp do you have? i know a catback will not affect your performance if you are under 350WHP.
    '04 Chevy Silverado LT 4x4 - intake, headers, full exhaust, zo6 cam, 799 heads, tune, leveled, 33's
    '00 Grand Prix GTP DAYTONA 500 - L36 block, S1X, intercooled, GenV, N*, headers, full exhaust, coilovers, 5 speed swap, stage 3+ clutch
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  3. #3 Re: Would I benefit from a 3" exhaust 
    Donating Users silverstreak's Avatar
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    No, your stock catback is fine.
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  4. #4 Re: Would I benefit from a 3" exhaust 
    GTX Level Member real diehl's Avatar
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    It will make moar annoying GM V6 drone...that's about it.
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  5. #5 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    Quote Originally Posted by CTKGP09 View Post
    how much hp do you have? i know a catback will not affect your performance if you are under 350WHP.
    i dont know know for sure. Its estimated probably 350-400...dont know for sure its just what i was told
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  6. #6 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    i have a 3" TOG down pipe with no cat from zzp. the previous exhaust sounded better without a cat so im kinda kicking myself for adding a magnaflow cat to the one i have now.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  7. #7 Re: Would I benefit from a 3" exhaust 
    The Blue One blueguy's Avatar
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    More like 300...or close to that...the best M90 build I think just cracked 400...and it was using a big cam and heads.
    Sold WBody's: '03 Blue GTP/'98 Green GTP/'98 Silver GT/'05 GXP
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    '89 Ford Mustang LX Notchback - LM7 5.3, 4L80, 9", HX40
    '04 Chevrolet Corvette MRM A4/LS1 - TSP LT's, 3"O/R X, AFE S2 CAI
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  8. #8 Re: Would I benefit from a 3" exhaust 
    youtu.be/xhrBDcQq2DM FoSHO99's Avatar
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    For the price of it, you'd be better off going with alky kit or cutout, save the money.
    2001 GTP PT61 Turbo, E85, Stock Motor
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  9. #9 Re: Would I benefit from a 3" exhaust 
    DUI BABY Bio248's Avatar
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    youll gain absolutely zero power. if you wanted to gain that 2 crank hp back just drop the catback at the track.
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  10. #10 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    seeing its a larger exhaust and i wont gain anything by it would there be a possibility of power loss. im not really looking to gain any power, i was just curious if it would. the exhaust i have now which only part of it is the R.A.T. system. its been a problem since i bought the car from the previous owner and the sound is just crap. if it could hurt the car i wont go that route and may have to sell the down pipe.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  11. #11 Re: Would I benefit from a 3" exhaust 
    Donating Users ls6velless454's Avatar
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    Apparentely these cars need a little bit of back pressure maybe if they were turbo I would go 3', but just change the tips and spend your money elsewhere.
    There is no replacement for displacement........unless you have a supercharger or turbo

    2000 Bright Red GTP Coupe GXP axle back, GMPP sway bar, NGK TR6, 180 stat. (Uninstalled Aeroforce Interceptor, DHP PCM, FWI, Gen V on the way) and still no pulley in sight.
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  12. #12 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    Quote Originally Posted by ls6velless454 View Post
    Apparentely these cars need a little bit of back pressure maybe if they were turbo I would go 3', but just change the tips and spend your money elsewhere.

    i tried that..it still sounds like crap. i need to replace the whole exhaust anyways seeing its back hacked up so many times from repairs. the monza system is supposed to have low back pressure. here is the link to it where i found it Monza 88-1484 Pontiac Grand Prix Cat-Back Exhaust - GP GTP
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  13. #13 Re: Would I benefit from a 3" exhaust 
    DUI BABY Bio248's Avatar
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    i always liked the stock catback with a glasspack instead of the resonator to give it some nice tone.
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  14. #14 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    i've got magna flow glass packs on it now but they have seen better days. the car used to give off a nice deep tone almost like a muscle car but over the years the pipes underneath started to rust and had to be replaced and the shop that did it is no longer around but they used a smaller pipe than what was on it when i took it to them.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  15. #15 Re: Would I benefit from a 3" exhaust 
    GTP Level Member SnowDrift's Avatar
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    Although I'm no authority on these v-6 engines, I would guess at no power loss running through a 3", but probably torque loss because of lower back pressure.

    I've never heard a v-6 with an aftermarket exhaust that sounded good to my ears. I'm "old school, though, and was raised around v-8 engines, so that is the standard by which I compare all others.
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  16. #16 Re: Would I benefit from a 3" exhaust 
    DUI BABY Bio248's Avatar
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    3" youll get no power gain or loss of torque.

    its just a waste of money and ends up sounding like crap.
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  17. #17 Re: Would I benefit from a 3" exhaust 
    GrandPrix Junkie CTKGP09's Avatar
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    STOCK catback FTW
    '04 Chevy Silverado LT 4x4 - intake, headers, full exhaust, zo6 cam, 799 heads, tune, leveled, 33's
    '00 Grand Prix GTP DAYTONA 500 - L36 block, S1X, intercooled, GenV, N*, headers, full exhaust, coilovers, 5 speed swap, stage 3+ clutch
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  18. #18 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    well that sucks..i dont have a stock catback seeing it came with a after market one when i bought it. i dont think it can sound any worse than what it does right now. it idles real nice with a deep tone but when you stomp the gas it can sometimes be mistaken for a fart can.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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  19. #19 Re: Would I benefit from a 3" exhaust 
    GrandPrix Junkie CTKGP09's Avatar
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    thats how GPs with aftermarket catbacks sound, good at idle and retarded with any throttle. you can probably but a glasspack for a resonator and build 2 yourself a cat back
    '04 Chevy Silverado LT 4x4 - intake, headers, full exhaust, zo6 cam, 799 heads, tune, leveled, 33's
    '00 Grand Prix GTP DAYTONA 500 - L36 block, S1X, intercooled, GenV, N*, headers, full exhaust, coilovers, 5 speed swap, stage 3+ clutch
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  20. #20 Re: Would I benefit from a 3" exhaust 
    SE Level Member BlackandSilverGTP's Avatar
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    oh well i guess i'll figure something out. thanks for the info everyone.
    98 GTP - VS Competition Cam, ported and polished M90 eaton w/ 3.1 pulley, ported TB, TOG headers and ported manifold, 2.5" RAT catback w/ Magnaflow mufflers and Magnaflow high flow cat, custom tuned PCM from ZZPerformance
    05 GTO - Stock for now
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