Help please! (Replacing stock cat)

**VejGTP** · 03-02-2010

(2004 GTP Comp G)

Alright, I posted a similar topic in the general tech forum. But I wanted to try a different approach and be more straight-forward with what I'm trying to do.

My check engine light came on a few weeks ago then went off and came back on a few days ago. I took it to my buddy at the shop he works at and they told me I'm going to need a new catalytic converter. If I let him do it, it will cost me around $500 for labor and parts.

I don't want to blow $500 on a new stock cat, especially since I wanted to get new headers/downpipe sometime in the future. So here's what I'm wanting to do.

-Get these headers from SSAC
Pontiac Performance Racing Products for International Sales from SSAutochrome Inc.
From what I understand these will work fine in my 04. But I'm not sure exactly how it will set up with my stock exhaust. Is this a catless DP that is included? If so, will this DP bolt/weld in place of my stock DP and cat?

I don't mind getting rid of the cat altogether, but if I need to order one to connect to the SSAC DP that is fine also. I just don't know what I need to do.

Also if I installed these headers would I need a tuned PCM right away or would I be alright without one?

I'll really appreciate anyone that can help me out. I'd like to get this work done ASAP so I can get rid of this check engine light and be driving again worry free. Thank you!!

**gpgo** · 03-02-2010

boy what a ripoff,$500.00 ( you can get a cat for around 65 and have installed for 30)

**VejGTP** · 03-02-2010

Yeah I guess the brand new cat was going to cost like $300+.. Just seems a little high.

**CTKGP09** · 03-02-2010

it is really high. buy a dp or just go straight to headers. u will spend so much less on something that will be beneficial...its a no brainer

**VejGTP** · 03-02-2010

Yep that's my plan. I'm ordering the ssac headers. Like I said in my first post tho, will the dp that comes with those work fine with the rest of my exhaust that's stock? And will I need to buy a tuned PCM if I get headers?

**Lawngoose** · 03-02-2010

Yes, it will bolt up to your "cat-back" pipes.

You always need a tune, even without headers..

**CTKGP09** · 03-02-2010

its not like the cars going to die the second u turn it on after a header install, but a tune is always a good idea

**VejGTP** · 03-02-2010

Hmm I see. Which PCM would you guys recommend I get? I'll probably buy some new plugs and wires this weekend and get my cai put in. I don't know of any places around here that program/tune chips so I'll probably get one already tuned..

04 gtp comp g

**CTKGP09** · 03-02-2010

intense performance is most likely your best bet for a PCM. i have heard good things about digital horsepower and overkill PCMs as well. as for plugs the s/c cars like copper plugs-autolites FWIW. now for wires i got MSD wires that have been working great for me so far. i found MSD wires to have low impedences compared to other brands and i have 8.5mm on my n/a

**VejGTP** · 03-02-2010

Alright, I'll definately look into those PCMs and I'll probably order one after I get this work done. Where do u get your plugs/wires? You just order them online?

**CTKGP09** · 03-02-2010

i got plugs and wires both from summit racing but there is alot of other places too. i have had an account at summit for about 5 years ha

**VejGTP** · 03-02-2010

Alright haha, I'll do a little research and compare prices. Do those auotlites have a #?

**CTKGP09** · 03-02-2010

this is from the "safley modding your 3800 powered car" thread....

and i quote-
Autolite 606 – Stock
Autolite 605 - 1 Heat Range Cooler
Autolite 104 – 2 Heat Range Cooler
Autolite 103 Race Plug – 3 Heat Ranges Cooler

**VejGTP** · 03-02-2010

Yeah I read that awhile ago but wasn't sure if I should get the 605 or 104's.. Are those all copper ones?

**CTKGP09** · 03-02-2010

i believe so, i cant see blue recommending anything else

**VejGTP** · 03-03-2010

Makes sense. Is there a big difference between 1 and 2 heat ranges colder?

Also, I was looking at the MSD wires you talked about and I don't see any that are compatable with the 2004 grand prix. Will it work the same even though it's a series III? Or should I look for different wires.

**CTKGP09** · 03-03-2010

different levels of modding require different spark plug heat ranges to keep KR down at agood level, which i thought was described in the modding ur 3800 thread.

i really dnt think the wires are any different from series III to series II, but not 100% on that...