Hello all. I am new to this site and this is my first post. I would like to say hello to everyone and am glad to be a new member in this community.

I have a 2000 GTP. All is stock except that the Ubend and the resonator have been replaced. I just bought TR55 plugs and 180F thermostat. I am going to get cold air intake and a throttle body spacer. I am wondering if I should get a 3.5 or 3.4 pulley for the super charger with these mods. Also, is the 3.4 will really be that bad on the super charger with my mods. I was also wondering what people thought about the exhaust. I have heard that the Cat and mufflers are good enough stock and that upgrading them is almost a waste of money. If they are benificial what muflers do you suggest (brand and size) and high flow cat do you suggest. My car is a daily driver and I would like it to last for a while. I dont want to mod it out and race it too hard or much. I just want some more power and would like to be able to beat most of those stupid little civics with the big ugly airplane fins that pull up next to me and rev their lawnmower sounding engine. (hope I dont offend anyone with a little foreign car) I am really dumb with any car that was made after 1982 and doesnt have a 305,350, or 400 motor. I am also curious about if I should run 91 or 93 octane with my mods and if I am on the right track with what I am wanting to do. Thank you all for your responses ahead of time.

You seem to be on the right track. As far as pullies go... a 3.4" pulley will be fine. The pulley really doesn't have any impact (to a degree) on the wear of the SC. You can throw a 3" pulley on there (I'm proof of that) and so long as you don't abuse the car, the SC will last a long time. The L67 is pretty much bullet proof.

You're going the right direction with the exhaust considering the level you're shooting for. I'd suggest getting a better downpipe (DP) and increasing the size of tubing from the stock 2.25" to 2.5" all the way back to the mufflers split. Also, replace that pipe with a true "Y" pipe versus that "T" that Pontiac uses.

Welcome and good luck,
Marc

I agree with Marc only I'd stay with the 3.4 pulley until you get some more supporting mods. The 3 inch might be fine in the winter when its nice and cold but come summer you might get more KR than you can shake a stick at. Enjoy yout GTP and welcome to the club.

Yeah... what HercMan said. I was just trying to point out (as lame as the explanation was) that your right foot has more to do with durability than the pulley size. If you're going to drop to 3.25" pullies or lower, supporting mods will be necessary.

Marc

Thank you all very much. Does anyone have any suggestions for the brand, type and size for the mufflers I should get. I read on ZZP that the stock mufflers are not restricive. Also, what should I do to replace the downpipe. Should I get a new one and where should I get it. or should I have the muffler shop fix it. I had my Ubend and resonator fixed with the O2 sensor put back in for only $50. and they did a good job.

For aftermarket mufflers it's pretty much personal preference. I'm installing a set of flowmaster 50 series.

This summer I'm picking up my second GTP. I've been mod'ing my current GTP for the better part of 7 years... back when the only company making aftermarket parts was SLP and then you couldn't get them unless you had a GTX. So, my current GTP has a bunch of old custom stuff on it.

I built exhaust from scratch and used 2.5" pipe from the cat back. The u-bend was replaced, the resonator was replaced with a Thrush glasspack, the "T" was replaced with a true "Y" pipe, the muffflers were replaced with Flowmaster 40 series, and I replaced the tips with oblong high polished slant stainless steel.

However, knowing what I know now, the GTP I'm getting this summer is going to have the following:

- TOG Headeers (already have these)
- R/T Gen I downpipe and high flow cat
- "U" bend and "T" replaced
- Tubing from downpipe to "Y" pipe will be 2.5"
- Tubing from "Y" to mufflers will be 2.25" (stock)
- Stock mufflers and tips.

After all the research I've done, I firmly believe this set up will work well. The custom exhaust I'm currently running sounds great from the outside, but drones heavily on the inside at cruising speeds.

Marc

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I just talked to a guy at a local performance shop and he was telling me that with a 3.4 pulley and CAI and the Ubend/resonator removed, colder plugs(NGK TR55's) 180F thermostat and throttle body spacer that He would not recommend upping my boost with a smaller pulley without doing something to increase fuel flow to the engine. He said that the stock PCM wouldnt adjust properly for that amount of boost and that it would be really bad on the piston heads. Does anyone have any thoughts on this? From reading alot of these posts it seems that a 3.4 pulley with the mods listed above and nothing done with the PCM and not increasing the fuel intake I would be just fine? What do you all think?

Also he said I would need bigger injectors. Is this true?

Ok just talked to another guy at another performance shop and he said I would not need larger injectors. He said depending on how my car reacts to the mods that I might need a fuel pressure regulator. What is everyones thoughts? Does anyone else have a fuel pressure regulator?

With those mods, I don't know if you would really need bigger injectors. I think your stock fuel setup should work fine for those mods since I don't think they are too extreme. If anything, I would maybe suggest getting a DHP PCM since it would most likely have all of those mods configured into it.

terapinn - see my response in your other post. BTW, considering your screen name, are from anywhere around the University of Maryland?

Marc

Terrapin.

You can go crazy talking to performance shops, and if they arent familiar with the GTP, then what they are telling you may not work well on your car even though its great for an LS1, or Ford 5.0 car.

Talk to and/or visit the websites of
ZZP, www.zzperformance.com
3800 performance www.3800performance.com
Intense www.intense-racing.com

Places like those above make their living doing stuff for our cars and KNOW what works and what doesnt. Their web pages are full of tech articles and info telling you what works what doesnt and how to go how fast for how much. There is a performance recipe page on the Intense website. check it out. The michigan group has a helpfull page too at www.migpc.com/Modifications/modifications.html.

IMO do the basic mods as you listed and get yourself a modular pulley system like DialURBoost, or ZZPs modular pulley system. There are a lot of others. Start with the 3.4 or 3.5 and see how things work out. That way if you want to go smaller, its easy to do so. If not, then you can stay where you are.

Get an LS1M (www.ls1m.com) or autotap or some sort of diagnostic software and see how your motor is running and reacting to the mods. You can learn a lot of that stuff by cruising the boards and asking questions. (where Im at now)

Smaller isnt always better. A a car can run faster with a 3.5 pulley and a 1 or 2 degrees of KR than a car with a 3.2 pulley and 10 deg of KR.

I dont think you will need to worry about extra fuel until you get nuts witht he car like larger blowers, cams, rockers, headers and tiny pulleys.

This is from ZZPs what not to buy page: Intense racing pretty much says the same thing.

Adjustable Fuel Pressure Regulator:
On many boosted cars fuel pressure needs to be raised as boost is added to compensate for extra air. The Grand Prix uses 2 methods to control fueling which render an AFPR worthless. The MAF sensor on the car reads the airflow and tells the PCM how much air is coming in and therefore how much fuel to deliver. As you mod and increase flow the MAF reads more and increases fuel. The stock FPR changes fuel pressure with boost. As your boost increases so does your fuel pressure. By changing this function by replacing the factory regulator you make your car impossible to tune. Adding fuel pressure doesn't change the maximum pressure because your stock pump is limited to low 60's in psi. So even though you might add 5 pounds at idle and cruising you're not adding that much at WOT. This makes tuning the car a nightmare. All the ZZP cars run stock regulators. If you have an aftermarket unit on your car, sell it and go back to stock. Thank us later...

Walbro fuel pump
If you have an M90 on your car then your stock pump is capable of flowing enough fuel. Our 97 GTP put down 410WHP using a stock pump, our 2000 Monte Carlo (L36 200HP stock engine) put down 387WHP with the stock pump. Changing your fuel pump greatly increases the chance of pump failure or problems due to hoses coming off. If your stock pump is still working keep it! Another down side to the in tank Walbro is the fact that it won't suck your tank dry. Your factory 17 gallon tank will be reduced to a 15 gallon capacity.

Jeff

Thank you all for your help. It has been so very beneficial to a guy that has never worked on a car with a PCM. I have always had 79 or older TA's and Z28's.

Marc, I am from Oklahoma City unfortunately. I got my screen name from a Greatful Dead poster when I couldnt think of anything. They have an old song called Terapinn station. LOL

Gotcha... I was just thinking that if you were from around the Washington, DC area you might want to attend a couple of the local get togethers. The WDCCGP was the first club on the East Coast. There are now three other clubs in that general area and all of them are pretty active. Particularly now that spring is around the corner. I don't know what kind of local interest there is in you neck of the woods, but see if there are any local meets you might be able to attend. Chances are that if there are any meets, some of the cars will have most of the mods you're looking at. You would then be able to talk with other folks that have already reached where you want to go and can ask questions and see stuff for yourself.

Good luck,
Marc