questions about my first supercharged car

**mngtp** · 02-13-2011

Im new here and I have just bought a 1999 Grand Prix GTP for my wife. This is my first forced induction car. It has 156,000 miles on it. I just bought NGK irradium plugs and stock replacement 7mm wires (the car is stock...for now). I know these questions have been asked before,
1.)what is the gap suppossed to be (or what do you recommend) on these plugs?

2.)do i need to transfer the metal sleeves on the current spark plug boots to the new wire boots?

3.)how often and how do i change the supercharger oil?

4.)what are some good cheep/easy upgrades for better performance/fuel mileage?

5.)are there any tips or recommendations you guys can give me to take better care of our GTP(is there anything special that i have to do to keep this car running and performing at its best since its supercharged).

6.)are the thrasher intakes any good? (i might be able to get one for free, i just need to swap the stock air box off of our car to a Bonnevile SLE)

7.)what catback exhaust or mufflers do you guys suggest for a good deep tone? (i dont want it to sound like fart cans like a few Grand Prixs I have heard)

Thanks in advance for the tips and help. I know that there were a lot of questions.

**matt5112** · 02-13-2011

1) 0.060"

2) no, not like they do anything.

3) 60 000 miles works.

4) Exhaust mods like a plog, downpipe or headers.

5) Always run 91 or higher, don't run a smaller pulley unless you're scanning all the time for knock retard.

6) They're okay, free works well.

7) stock, Dynomax, Borla XS

**blueguy** · 02-13-2011

Welcome...

first off...click the link my signature for info...I'll answer the ones you asked tho here...

1) .055"...get autolite 605's since you plan on modding.
2) No...throw them out.
3) I do mine every 30k...but I'm anal...most people do it every 50-60k...it takes 2 full bottles of GM S/C Oil or Mobil1 0-20W Full Synthetic.
4) See link in my signature...
5) High octane fuel...a good tune...dexcool delete mod and new LIM gaskets should cover it.
6) Meh...just throw a cone filter on the throttle body and be done.
7) Keep the resonator. That's how it's done.

**blueguy** · 02-13-2011

Damn you.

**matt5112** · 02-13-2011

its mobil 1 5W-30. not 0-W20.

Dex isn't bad if you flush it regularly.

Also yeah....

Invest in some aluminum/metal LIM gaskets be they GM or Felpro, as long as they're metal and you flush your coolant you should be good for another while.

Might as well change out your valve cover gaskets and grommets while you've got the whole thing apart though.

Change the S/C fluid, and the coupler for the green one you'll find on ebay or ZZP.

Personally wouldnt trust ebay though.

Oh and replace the coolant elbows while you're in there.

With that many miles i'd check the belts thoroughly for signs of wear.

**blueguy** · 02-13-2011

No...it's 0W-20 Fuel Economy Full Synthetic.

I know because I use it.

http://www.cleanmpg.com/photos/data/500/Picture_020.jpg

**matt5112** · 02-13-2011

ask the GM parts guy TLS for the picture of the GM memo.

**Fivefingerdeathpunch** · 02-13-2011

pretty much what they both said.

and NEVER get chambered mufflers like flowmaster.

Id stay with stock mufflers, cuz pretty much all other muffs sound like butt.

wut part of minnesota you from???

**blueguy** · 02-13-2011

I think stock mufflers sound like butt.

**mngtp** · 02-13-2011

edit:
I actually got the autolite XP's. is the gap the same for these? The NGK's are for my 2000 cavalier.

**blueguy** · 02-13-2011

XP plugs aren't great.

Just regular old junky Autolite 605's man.

**mngtp** · 02-14-2011

Originally Posted by Fivefingerdeathpunch

pretty much what they both said.

and NEVER get chambered mufflers like flowmaster.

Id stay with stock mufflers, cuz pretty much all other muffs sound like butt.

wut part of minnesota you from???

Im originally from Blaine, but I live near Forest lake now.
We just wanted it to have that stock deep tone, just a little louder. She actually asked me about the exhaust before I could even say anything lol. She read my mind.

**matt5112** · 02-14-2011

xps are iridium.

you're not supposed to gap iridium plugs.

**Reptile** · 02-14-2011

Matt, I've used the ebay couplers for years, and never had an issue with them.
The only difference in them is they don't have the fancy machining done around the holes, but they're the same thickness and are made out of the same material.

Bargain shopping FTW

**matt5112** · 02-14-2011

Good to know, thanks!

**mngtp** · 02-14-2011

Well I looked at bluegtp91's write up. I returned the irradiums for the autolite 606's. I was just wondering why a couple you guys said to usse AL606's over the irradiums? Irradiums are $7 and the 606's are like $2. I just want someone to explain why I shouldnt go with the irradiums?

**matt5112** · 02-14-2011

Apparently these engines like copper plugs.

Rather than waste $60 to find out, i thought i'd just trust the experiences of others.

**txslow6** · 02-14-2011

Originally Posted by mngtp

Well I looked at bluegtp91's write up. I returned the irradiums for the autolite 606's. I was just wondering why a couple you guys said to usse AL606's over the irradiums? Irradiums are $7 and the 606's are like $2. I just want someone to explain why I shouldnt go with the irradiums?

I bet 95% of the people on this forum couldn't tell you why-

Seriously.

Copper plugs in general are more conductive when it comes to electricity. Platinum and Iridum perform at a lower level, but tend to overheat. Longevity wise the platinum and Iridum will be better suited (hence why they cost more), but for overall performance you want to stick with copper plugs.