Yea you should be able to run a 3.5 with little Kr. As you already know and as i will repeat make sure you scan. If you drop and are still getting Kr you should be able to easily reduce it to safe levels with a downpipe. If you want to be extra safe a plog and a PCM will let you run the 3.5 with virtually no problems. That in mind every car is different but the above is usually true for most cars.

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1999 GTP (70k miles): Thrasher CAI, MSD ignition coils, pcm. Soon: 3.5" Quickchange pulley, alcohol injection, autolite 104's, 180* thermostat.

Thanks for your advice. I'll pick up a ZZP PCM 1.0 as well to be on the safe side.
I don't think its legal to swap ANYTHING before the cat here.

Bad choice, and certianly not the 'safe' side.

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2.8 Pulley, Intense IC, P&P Gen V, Machined Intake, Intense PCM, 65lb/hr Injectors, N* Throttle Body, 1 3/4" Headers, 3" Exhaust, Intense Shift Kit, 3.69:1 Gears, 4000 Stall, N20

Why's that? In the main part of the forum is says the PCM is a recommended upgrade for a pulley swap. Something I'm missing?

The upgraded PCM isn't the problem. It's the fact that you have plans on purchasing a ZZP PCM thats the problem.


ZZP PCM's have caused way too many issues for too many people. It's pretty well known that when looking into buying a aftermarket PCM that you need to stay far..... away from the ZZP ones.

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2.8 Pulley, Intense IC, P&P Gen V, Machined Intake, Intense PCM, 65lb/hr Injectors, N* Throttle Body, 1 3/4" Headers, 3" Exhaust, Intense Shift Kit, 3.69:1 Gears, 4000 Stall, N20

I know you missed the part where the only exhaust mod was a ubend delete. For a 3.5, at the very least a DP, needed to be added to his list. Still likely even with those mods, the only way to run KR free would be a PCM with a 10.6:1 AFR with reduced WOT timing. A combination of slow. I just don't get why after as much time as gone by and as much information available people are still recommending pulleys that are too small for the mods, instead of working the in order of optimum AFR>Timing and then go with the pulley that fits the build.

OP-go with an Overkill PCM :: Overkill Motorsports ::

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04 Indy SS build #972
XP, TOG's, Lightning injectors, 2.8 pulley, 105 CC springs, Wizaired, 3.29 gears, tripleedgeperformance ported blower, machined LIM, 180* tstat, RS12YC@.053, FP rewire, Alt rewire, stage 1 V boost, PRJ wires, Stage 2 IC

^^^Listen to his advice, he knows what he's talking about. Fueling>Timing>Boost

I would highly doubt that you would be able to run a 3.5" with that mod list. If you are dead set on dropping pulley sizes, you should at least look into getting a front power log since the stock manifolds are ****. To be honest if I were you I would just go ahead and get some headers, since you will probably want them in the future anyways just save yourself some trouble and get them now (especially since the new ZZP headers are out and people are going to be selling their headers for cheap). If you get some headers you should be able to run a 3.4" no problem with your mods.

Oh and the reason why a PCM would be a bad idea with a 3.5" and your modlist is that an aftermarket PCM raises your timing and since you would probably be seeing KR anyway with the 3.5" it would result in even more KR.

There is a slight possibility that you can run that 3.5" without any KR, but you can never know for sure without scanning.

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2000 Silvermist Grand Prix GTP Coupe

Mods-Custom Thrasher CAI|Ceramic Coated S&S Headers|3.4" pulley|Powrtuner|WP Underdrive Pulley|Alternator & FP Rewire|PRJ 10.4mm wires|ZZP 6000K HIDs|F-Body brakes

GET HEADERS SAVE YOUR MONEY

Agree

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1999 Silver GTP~HP Tuners~XP cam~ZZP FS Intercooler~#4 FMHE~ZZP 78mm Billet Throttlebody~LQ4 MAF~Lucas 42.5's~ZZP SS Headers~2.8 MPS~PRJ fuel logs~Ported & Polished S/C~TDCRacing FWI ~Built Tranny-3.29's-7/8's chain-Intense forged Input Shaft~

Running mid-high 12's
Get you're TDCRacing Fenderwell Intake Today!

You need to scan first. nobody can tell you what to do or what is best for you to do without scanning. So let that be your next mod.

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1999 Silver GTP~HP Tuners~XP cam~ZZP FS Intercooler~#4 FMHE~ZZP 78mm Billet Throttlebody~LQ4 MAF~Lucas 42.5's~ZZP SS Headers~2.8 MPS~PRJ fuel logs~Ported & Polished S/C~TDCRacing FWI ~Built Tranny-3.29's-7/8's chain-Intense forged Input Shaft~

Running mid-high 12's
Get you're TDCRacing Fenderwell Intake Today!