GTP guys:I need your help

[281cubes]

Howdy. Doing some research into modifying an '02? GTP. It belongs to a friend of mine and I thought you guys would be able to help. Looking for the basic upgrades and this is what I've come up with:

3.4" pulley
180* T-stat
Autolite 104's gapped to .055
ZZPerformance PCM/ECU
Wizaired CAI

Now, in eliminating the U-bend, I run into some confusion. This car is most likely going to retain the stock headers - at least for now - but will be looking at an aftermarket cat-back. It needs to stay emissions-friendly and keep KR (knock retard) at a minimum (obviously), but a cat is a must. So...

What cat-back is a popular upgrade? Am I best off getting a new downpipe with a high-flow cat built into it to both eliminate the u-bend and still pass emissions? If so, what size/diameter? (bolt-in, 3" into a 2.5" was my thinking) Is there any need to get a trans cooler for this level of modification? :shrug:

I hope this is clear enough to make sense out of. I took a self-taught crash course on GTP's this afternoon in about an hour, which is how I came up with the mod list above. I think I did okay.:coolman:

 

[philip]

Ok ill be the asshole. The name of the site is SVTperformance.com not GTPperformance.com.

 

[HotRodK]

www.clubgp.com

I had a GTP a few years ago and I learned a LOT at that site.:thumbsup:

 

[4u 2 nv]

i would run the 3" DP with no cat and a dump for the track with stock catback on the streets. I dont prefer the sounds of these cars with aftermarket exhaust. the pulley is good. the 180 is fine and the plugs are very popular. Is that ZZp ECU the same as the DHP (digital horsepower style) tune? either way its probably good. however you might wanna try TOG headers...most guys get 20 FWHP on a stock car with headers..other than that your mods sounds pretty standard. on some good tires with good air id would expect some srong mid 13's to possible a low 13 second time slip with perfect condition and alt.

 

[dredg9]

make sure you do something with the exhaust because my buddy has 3-4 degrees of kr with a 3.4 pulley, intake, downpipe, pcm, plugs,thermostat. With those mods his car was side by side with an srt 4 until 100.

 

[281cubes]

Ok ill be the asshole. The name of the site is SVTperformance.com not GTPperformance.com.

Noted. However, that's why I titled the post as I did; to appeal to the members of SVTP who might also own/have owned a GTP. Keep in mind that not everyone here - much like you and I - owns an SVT product. There's a lot of car experience here and I thought I'd tap into that. If nothing else, when I need to know about F-150's, I know who to come to.:-D :beer:

To everyone else, thanks for the feedback.

4u2nv - I believe it said that this particular PCM was calibrated with a 3.4" pulley in mind. Thanks for the header advice.:beer:

dredg9 - I'll certainly keep that in mind. It's a daily driver so risking excessive KR is a major concern.

HotRodK - Thanks. I was fartin' around on GTPworld, which is decent, but seems kind of dead. :shrug:

 

[GH1086]

i would run the 3" DP with no cat and a dump for the track with stock catback on the streets. I dont prefer the sounds of these cars with aftermarket exhaust. the pulley is good. the 180 is fine and the plugs are very popular. Is that ZZp ECU the same as the DHP (digital horsepower style) tune? either way its probably good. however you might wanna try TOG headers...most guys get 20 FWHP on a stock car with headers..other than that your mods sounds pretty standard. on some good tires with good air id would expect some srong mid 13's to possible a low 13 second time slip with perfect condition and alt.

No, no, no, no. If you want the car to sound like shit, get rid of the cat. The 3800 is quite possibly one of the worst sounding engines I've ever heard. The best mufflers I ever heard on one (still crappy sounding but with the least drone) were Borlas. If you get rid of the cat it will drone like crazy. I would just take the car to a local muffler shop and have them replace the u-bend and weld in some Borla mufflers.

Make sure you keep a really close eye on the KR too.

Also that car will be high 13's at best, not mid or low 13's. If you got to ClubGP you'll see that it takes at least a cam into the 12's and there usually not tiny cams.

BTW, I used to own a GP, so I have experience with this.

Edit - I find it slightly ironic your SN is RedZoomer too, on ClubGP a guy with the SN Zoomer (also the owner of ZZP) has the fastest FWD GP in the world, well at least it used to be last time I checked.

 

[SinisterSHO]

www.wbodystore.com Guy who owns that used to sell SHO parts. Decent guy with good service. Knows what hes doing.

 

[281cubes]

www.wbodystore.com Guy who owns that used to sell SHO parts. Decent guy with good service. Knows what hes doing.

Thanks, dude. That's relatively close to me, so that's a huge plus. Appreciate it.:beer: