New to me 99 GTP got some ?s

Hi I just bought a 99 gtp the other day and i dont know alot about it. Neither did the previous owner. All i know for sure is it has a full exhuast and header setup. All SLP and a cold air intake which im not sure what it is. But i think it has more done to it because it has some serious power for a GTP. A girl i dated in high school had one. And i had a perfect running stock SSEi for a while. And it has a vaccume leak somewhere and it would still walk the other s/c 3800s i have drove. I dont know alot about supercharged cars and i would like to find out what all is done to it. I know people change pulleys. So is that as simple as measuring the sc pulley? I need to fix the vaccume leak (buying new hoses) to be sure but it seems like there is a slight spark knock. The guy before me might have been running 87 octane. I dont know but he seemed like somebody who would(carefree college type). I know there isnt a aftermarket cam by the sound. Not sure about computer management but that will be my first performance mod if it is stock. It feels like its closer to 300hp than 240 just by my experience with built older cars. But i tell ya i really like this car. I loved my bonneville and wished i still had it but the gtp being lighter weight makes it better performance and handleing wise. And i only gave 2 grand and i give the exterior about a 8 with only some little dings in the door and interior a 7 w/ a tear in each front seat and some broken panel clips but has black leather( awesome). And its white. Which i have a curse on me to only own white cars. Ive had ten cars nine have been white the odd one out never seen the road with me in it. Own a white supra and explorer right now. Weird huh? So im pretty happy with the deal. Anyway hope everyone on here is doing good and thanks for any advice in advance

use the enter key.

Welcome, sounds like your off to a good start. Just gotta figure out all your mods and go from there good luck identifying all the stuff under the hood.

The guy i bought it off of was selling a 2000 gtp too for 1500. Wished i had the money too buy both because i dont think 3500 is too bad for 1 car but two of the would have been great. It had alot of miles though 248k i believe. Mine has 148k

Well, I swear I just wrote that. We are a lot alike, man! Love Supras and 7 out of my 10 cars have been white or pearl. Have had multiple 3800's and 6 years ago, bought a modded GTP and had no idea it was modded till I drove it and realized something was different. As for the pulley, take the circumference and divide by pi (3.14). That will give you the size of the pulley. Also, I'd recommend an aeroforce scan gauge, or the like. Best investment I made so far. I learned a LOT about my car because of it. And the vac lines were the first thing I replaced when I bought the car. I got these silicone lines and 6 years later, they're still in great shape. And they are really thick, so they will not collapse like other silicone lines do. Anyways, Welcome! Pics of Supra!!!
Silicone Hose Kits - 7 colors

Thanks, appreciate the info. The supra is a 84. Im going to start doing some work on it to do a 2jzgte swap but thats going to be a long strung out process. Thats why i bought a new car so i can park it and im glad i did. Love the new gtp! I wish there was a reasonable option for a manual swap but i do like autos for normal daily use. Also had a white 91 rx7 turbo that was a very fun car. I have a few pics of the supra somewhere on my computer. If i can find them I'll upload and post'em

Welcome to the site.

Hi I didnt want to start a new thread but like i said not sure of the mods on the car. I fixed the vaccume leak it has. I didnt get around to measureing the pulley for some reason. But i did get a few 0-60 times through a phone app. Not sure how accurate they are but ive heard .08 of a second. They ranged from 5.9 to 6.2 seconds. Only mods i know for sure is a cai, and slp headers exhaust. Do these numbers sound like there is more work done to it than i know of. And it sounds like there is some pre-detonation going on at idle but very slight. But car opens up well and sounds good. But i think im going to take it easy her till i get that sorted out. Just couldnt resist see what she would do.

its incredibly unlikely you have detonation at idle.

Pre-ignition typically results in instant engine failure these days.

a 0-60 of ~6 seconds suggests there is more done to it, but maybe not.

Depends on tires, if there are rockers and other small things like that.

Oh ok. But its a slight tick of some sort.

if you have a open cone air filter you will now hear every single internal noise the engine makes, even louder from a cold start.

Exhaust leak maybe?

Filters still on the box but its worse at a cold start then seems to go away. There is a hole cut out of the airbox i guess for the sound

thats the way our 3800 s/c engines roll, just ignore it.

most of us even have some nice lifter rap at start up, i get it once in a blue moon, i'll get 3 not so nice sounding rocker claps and then its gone.

usually due to a lifter loosing pressure, and then it collapse until oil pressure builds it back up, then it stops. its kinda normal for the 3800.

That makes me feel better. I didnt get that w/ my ssei but it was bone stock w/ 63k and was never abused it whole life. Atleast until it met me that is

with a stock intact air box you hear a lot less of it.

Couple more questions? When my car is low on gas it can jump up to a half tank or more when im going on a curvy road making it impossible for me to tell how much gas i have. Do they all do that? Also is there any drawback to leaving the performance shift on? Like does it decrease your gas mileage significantly during normal driving? I have to say the only thing im not overly impressed about the gtp is the transmission. Will a aftermarket pcm make a big difference? I think im going to buy one from intense racing unless someone else make a better product but they are the only site I have looked at so far.

your fuel tank sender is on its way out as far as the gas gauge goes.

perf shift you can drive like that, it just make it shift a bit firmer/ quicker. also make the gears a tad longer when wot.

a shift kit will make it shift nice and firm.

with you not knowing fully what may or may not have been done it would be hard to order up a canned tune. you need a mod list for the tuner.

a in car tune may help. im no tuner so ill leave that one for the pro's here.

Yeah i was reading testimonials on their website and they were saying that they helped with 4-2 and 3-1 gears shift. Which Ive noticed on mine that sometimes when i put my foot down it will hit another gear before it hits the power gear. But it could just be my trannys a little wore but it doesnt slip. I dont know the only other auto i have drove in a long time is my explorer but its tranny has slipped and jerked since i bought w/ 20k on it and its still going 100,000 miles later

Found out today it has a 3.0 in pulley. I didnt measure it but i got the part no tr2000 off the pulley and thats what came back. I read that this is not safe without a intercooler. Im not trying to build a race car right now. Should i revert to 3.5 or something more tame.