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Good mods for a currently stock '99 GTP?

Centauri

Centauri

New member
It's looking like I have a cracked exhaust manifold (already had the gasket replaced) and considering how inexpensive the Speed Daddy headers are, I figured I'd just go with those instead of OE-replacement stuff. Which got me thinking...

Without having to reprogram anything, what are some other mods I could do on a reasonable budget?

As I understand it, the headers alone will net a performance increase? But do they necessitate that I make a cold air intake setup?
 


search the how to topics and make your own intake. Basically it's just a cone filter strapped on the end of your TB. What Year car btw? Also, miles, how it runs, etc.

Hard to suggest stuff when we don't know anything about what you drive.
 
Well, I put '99 GTP in the title? :confused:

It just rolled 100k and runs perfectly now that I've replaced all of the faulty sensors. It was a single-owner garage queen until 8 months ago.
 
Since it's a 99 (my bad), with low miles, go with your basic 3.4 setup. Headers, Pulley, intake, and if you choose (It's recommended) a tune. You can get a canned tune from overkill, reptile or intense. Those are the good ones.

Also, plugs(autolite 104's, one heat range colder), wires, and 180* t stat.

Start there.
 
Centauri said:
It's looking like I have a cracked exhaust manifold (already had the gasket replaced) and considering how inexpensive the Speed Daddy headers are, I figured I'd just go with those instead of OE-replacement stuff. Which got me thinking...

Without having to reprogram anything, what are some other mods I could do on a reasonable budget?

As I understand it, the headers alone will net a performance increase? But do they necessitate that I make a cold air intake setup?
Click to expand...

And this BTW, is probably the most worthwhile mod you can get. Tunes open up a GTP.
 
Thanks. :)

Okay, that's not bad. $150 after refundable deposit from Overkill.

Will any of these mods start throwing codes without a tune? So... CAI, headers, tune and a pulley; what would that net me in WHP (approximately)?
 


No you shouldn't throw any codes with any of these. Unless you run into issues with your headers and the o2 sensor. If that happens just get an extension from zzp and you'll be fine.

WHP is very subjective. But realistically, with minimal knock (get something to scan for knock, like the torque app) going from a 3.8 to a 3.4 with headers and a decent tune should get you anywhere from 25 to 40 whp.
 
OH and read the safely modding your 3800 thread. It's a sticky in the general tech section i believe.
 
Most people on a gen 3 go down to a 3.4 after headers. Honestly it depends on your knock. scan and find out. Get the Modular pulley system.
 


They'll work for stock but once you start increasing boost you'll want one heat range colder plugs. I like autolite 104s. Search the forum and you'll different answers. It's all subjective.
 
Alright, I'll pace things out.

For clarification though, what do you mean by check my knock? Headers are going to cause my engine to start knocking? </noob>
 
I love the /noob btw. Ha!

Knock retard is a big hindrance of our cars. There are many threads on it so I would say searching would do you better than me trying to explain it all in a few words. Basically more knock= car goes boom. All cars knock, even stock ones. That's why we scan and that's why a good tune is the best mod. Check some of the stickys around here, there is some good info about knock.

Btw, headers kill some knock. They're great for reducing it to almost 0 on a stock car. Once modded though it will knock again.
 
Gotcha. :)

A tune would still be beneficial even if I don't do the pulley or anything further, right? I may stop at air intake, thermostat and headers.
 


Or just skip the headers and get a 3" downpipe. It's cheaper, a forth of the install time, and you won't have the upkeep that most headers have...example: exhaust leaks, leaking flex, stupid downpipe hitting the ground, extending the o2 sensor harness, etc.

You won't need the headache of headers if you're just doing a tune with an intake and a tune. If you want to add a little more flow, then toss a PLOG from ZZP on it too.
 
blueguy said:
Or just skip the headers and get a 3" downpipe. It's cheaper, a forth of the install time, and you won't have the upkeep that most headers have...example: exhaust leaks, leaking flex, stupid downpipe hitting the ground, extending the o2 sensor harness, etc.

You won't need the headache of headers if you're just doing a tune with an intake and a tune. If you want to add a little more flow, then toss a PLOG from ZZP on it too.
Click to expand...

Remember Blue, part of the reason he wants headers is to replace a cracked exhaust manifold. Downpipe won't help him with that.

I think headers are great by themselves, but getting an MPS with a 3.5" pulley would not be a bad idea.

I'd highly recommend you get a tune with the pulley drop. My 99 GTP had KR with 3.5, hia, and headers, until I tuned it. I'd say she actually ran quite a bit better with a 3.6 pulley and timing added. Obviously, different strokes for different cars.
 
I keep going back and forth on the idea of doing the pulleys. So the ZZP modular system is the best to buy, right? I'm only hesitant because it's gonna require new plugs (which I just replaced) and, if I understand correctly, new belts? Well, which belt would I need?

Isn't there some special tool for the pulley replacement? I doubt the friend of mine who is going to do the work will even have that.

I also seem to recall reading that dropping the pulley size drops city-scooting performance, but increase top-end? I'm not looking to drag the car I just want more pep out of it and most of what I do is city driving.

Thanks for all of the help, people. :th_thumbsup-wink:
 
I ran a stock length belt on my 3.5 pulley.

There is a special tool for pulley removal/installation. I might know of someone local to you that has one... :th_winking:
 
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