Thread: 99 GTP Mods questions.

So I have a 99 GTP. The current mods are 4" intake, 3" downpipe with cat and u bend delete, 1 degree colder spark plugs with upgraded wires, I've wrapped the crossover and will be adding a custom throttle body heat shield, wideband o2, and a custom tune.

My goal is to get 300+ WHP. So I'd be happy with 305 WHP. I am looking into buy the VS cam from ZZP because I will be mainly driving it on the street and maybe once in a blue moon take it to the track. My list of purchases are as follows.

* VS cam
* New Springs, Seals, and locks. Going with stock or 85lb springs.
* 3.4 modular pulley
* New custom tune

My real question is should I purchase 42.5# injectors with this setup or will the stock 33# handle them, and should this break the 300 WHP mark?

If this is already a thread sorry for reposting.

I think you can get 305 without doing a cam. to my knowledge a full exhaust and intake with a gen 5 supercharger and 1.9 rockers with a 3.4" supercharger pulley will get you there.

Originally Posted by 99pgpgt

Stock l67 injectors are 36 lbs btw

Everywhere I've been has posted that they are 33 lbs stock. Plus I've replaced mine and I purchased new 33# injectors. Should have bought larger but was hurting for cash.

Originally Posted by Fivefingerdeathpunch

Wont even come close to 300whp, maybe 250........maybe....... with what you have listed.

Even with those mods, you may not even get 300 WHP more around 270-280 whp, and when you get that high, transmisson failure rate goes way up.

I agree with not reaching 300 WHP it was a goal that I'm shooting for and will continue to hunt it down if I don'r reach it with this upgrade. So yes I agree I will most likely land in the 270-290 area. Thanks for the transmission warning. It was replaced approximatly 15,000 miles ago so should be ok because I rarely race or go to the strip.

My main areas where I was having issues on proper information were injectors being able to hold up and the valve springs. I've read a few times but actually having someone say it helps that injector sizing really just depends on the car. So I'll just have to hope mine work or go with a mild tune and save up for new ones after the build. As for the L76 springs I was looking at upgraded springs so I avoid valve float at all possible. I have one question and that is will the L76 springs work with stock retainers or will I need new ones?

Originally Posted by johntremell

I think you can get 305 without doing a cam. to my knowledge a full exhaust and intake with a gen 5 supercharger and 1.9 rockers with a 3.4" supercharger pulley will get you there.

I am looking at avoiding the Gen V supercharger for now as I am a broke college student. I may purchase it later in life when I can afford to really add performance. Thank you for your reply.

You will need new retiners to run the l76 springs.

You will need an intercooler and a much smaller pulley to reach 300whp with the VS cam. Preferably a stage 2 intercooler.

Originally Posted by newbiegtp

I am looking at avoiding the Gen V supercharger for now as I am a broke college student. I may purchase it later in life when I can afford to really add performance. Thank you for your reply.

A cam is 800-900 if you do the install yourself.

Intercooler its well over a grand. You'll still want a larger tb by that point.

that's another 300.

Gen v is only another 300.

Use l76 springs and ls1 retainers.

All in all the comment I quoted its funny.

You'll need injectors but I don't recommend the Lucas 42.5's.

Get 60's or better ~40's.