Ok, i messed up and put at 3.4" on my '04 GTP right off the back, i knoew nothing about knock retard, and simply though a smaller pulley would help out time wise and create more power. After that everyone told me to take it off and put a largr one on so i wouldnt keep hurting the motor, but instead i bought a Front PEM, 3" Catless DP, had full 3" exhaust done with magnaflows, ZZP 1.0 PCM, made a FWI, and added a TB spacer. Me and a technician at work went down on the highway with a Tech 2 and at WOT it had not one lick of KR, through 1st, 2nd, and 3rd gear. It fixed my KR issue, but killed my fuel mileage, and i hated the way the car sounded with no cat. I had a magnaflow cat put on recently, and today me and the same technician went back on the highway, and on WOT right after 5000 RPMS it jumps from 0 to 2 KR, and then right at the shift it jumps from 2 to 4 KR, so self-explanitory, the converter it causing restriction on the motor, and pulling timing, causing KR. Today, when i get my answer, im buying a MPS but i need to know if i should get a 3.5" or 3.6", i need some help from people who know what theyre talking about, its very much appreciated..

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Take the CAT off and install a resonator, keep the pulley. If you're worried about gas mileage, go back to stock.

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2005 Grand Prix GTP CompG
[url=http://www.cardomain.com/ride/2457141]Check out my ride[/url]

well if wanted the cat off, i wouldnt have put the money into getting putting the one on, if you dont have any recommendations, then so be it, its a simple question, should i go with a 3.5" or 3.6"?

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If you have acces to the the tech 2 i would put on the 3.6 to start and scan it and if there is no KR drop down to the 3.5 and scan again. I think the safe bet would be the 3.6 but you coulb probably get away with the 3.5, wont know till you scan.

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2002 Grand Prix GTP
3" ZZP DP | CAI | ZZP 1.0 | 180 T-Stat | GMPP Handling Kit | 6000k HID |

Ya i was thinking that, i live in northwest florida, its really not that cold alot, is there some sort of way to know how much KR you create by the pulley size your dropping or increasing?

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i think 3.5 should be fine..
i wouldnt worry about 2* or KR.. honestly ive seen completely stock cars scanning around 7* of KR..

i would say up to 3* of KR you should be fine.. once you're over that then you might need to scratch your head a little and see whats going on..

i drove my 03 GTP with a 3.4 for over a year and a half with around 4.5* of KR at WOT and nothin happened.. sold it and shes still fine..

again.. thats JMO

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05 Bonne GXP, click for cardomain


somethings just cant be replaced ... good times...

I believe that colder air is denser wich makes more power but can create more KR than hotter air if you dont have the proper supporting mods, someone correct me if im wrong please. Most of the time a smaller pulley will make more kr if you dont have the supporting mods for it but every car is different so you wouldent really know till you scan. Also you have the GenV which makes more boost because it is more efficient so you would have to factor that in when choosing a pulley.

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2002 Grand Prix GTP
3" ZZP DP | CAI | ZZP 1.0 | 180 T-Stat | GMPP Handling Kit | 6000k HID |

doc02gtp you are correct but it doesnt matter how many supporting mods you have you stil need a proper tune to run everything..
thats why i recommend going down one pulley size and scan.. then another size down then scan... and so on.. i had all the supporting mods for my 03 to run a 3.4 but when i took my overkill pcm (not tune.. just a pcm) out.. that 3.4 was doing me nothin but a louder whine and more KR.. no performance at all

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05 Bonne GXP, click for cardomain


somethings just cant be replaced ... good times...

well thanks for the input, just forked up $112 and ordered a ZZP 3.5 MPS, when i was scanning, it was about 55* outside, so ill get this on, see how my KR works out, run it at the track, and hopefully, smooth sailing from here on out...

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Alright good luck... let us know how it goes

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2002 Grand Prix GTP
3" ZZP DP | CAI | ZZP 1.0 | 180 T-Stat | GMPP Handling Kit | 6000k HID |

interested on how it goes

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ya me too, i ordered it today, probably be here wednesday/thursday, and ill be racing it at the track next friday...

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Go with a 3.5, if you car was running well with the 3.4 and no cat, the 3.5 should give you a nice response

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Click HERE for updates and pic of the car!

one 10th of an inch size of a pulley is not going to make much of a difference.

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2005 Grand Prix GTP CompG
[url=http://www.cardomain.com/ride/2457141]Check out my ride[/url]

You'd be surprised...

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'02 Galaxy Silver GTX Coupe. SLP Headers, SLP cat-back exhaust, SLP 1.8 RR, ZZP 3.4/3.25" MPS, SLP hood, SLP CAI, Overkill PCM, 180 t-stat, SSIC, S1 TB, AL 104's, F/R STB's, F-body calipers.

If you just wanted a little more power, I would of gone with the 3.6. If you are serious about modding get a tuner or find someone to tune it for you timing>boost. My car absolutely loves timing.

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99 GT (Stock - DD) & 04 Comp G (A Few Mods)
New 1/4 mi. PB @ Pontiac Nationals 2009: 12.79

a buddy of mine on the local forums said that he has HPT software and if i pay for the credits, hed hook me up, i have a ZZP 1.0 PCM, but i highly doubt they tune it as good as it gets. Just have to do it one step at a time.

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Not too much surprises me.

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2005 Grand Prix GTP CompG
[url=http://www.cardomain.com/ride/2457141]Check out my ride[/url]

There's a first for eveything...

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'02 Galaxy Silver GTX Coupe. SLP Headers, SLP cat-back exhaust, SLP 1.8 RR, ZZP 3.4/3.25" MPS, SLP hood, SLP CAI, Overkill PCM, 180 t-stat, SSIC, S1 TB, AL 104's, F/R STB's, F-body calipers.

ya hes got a turbo/nitrous v6 camaro, and hes tuning his own car, so ya i think it would be worth a shot

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This is true but there are only so many 'everythings'.

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2005 Grand Prix GTP CompG
[url=http://www.cardomain.com/ride/2457141]Check out my ride[/url]

Riggggght...

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'02 Galaxy Silver GTX Coupe. SLP Headers, SLP cat-back exhaust, SLP 1.8 RR, ZZP 3.4/3.25" MPS, SLP hood, SLP CAI, Overkill PCM, 180 t-stat, SSIC, S1 TB, AL 104's, F/R STB's, F-body calipers.

do you have a PLOG or a PEM?

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04 Comp G. Sport Red. SPO.
SmoothFlow 3.6MPS | PRJ Tune | Powerlog | 3" DP | Wizair | PRJ 10.4mm wires/Autolite 104's

Where in FL are you? I know of some of the V6 f-bodies, who's car?

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00 GTP Daytona

well everytime i try to log in, it wont let me, reset the password and it wont work, so i made another profile. I do have a Front PEM and i live in Crestview Florida, about 30 miles north of Fort Walton Beach, and Destin.

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