I would wait until you have two cars. Have a car that goes no further under the hood than an intake, exhaust and a tune. I have wound up so many times with 3 damn project cars and none running/drivable

That said, if you wanna say "fuck off dude on Reddit. I'm bout that Grand Prix life!" I can help. First off, how crazy are you trying to get? That platform isnt i deal for max power. If youre looking for a fun cruiser that's fine but I wouldn't expect more than 325 hp in that to be useful without some serious driveline modification. I know a guy who had to build his trans get a torque converter and get beefier axles and it blew up anyway. I think he had an 04 GT. He was in it for like 25 grand in the end. So pick where you wanna be at on the sane-lunatic spectrum there

After the basic suspension, and breathing mods (intake and exhaust) and you have a daily and you still wanna mod that specific car, you will want to explore forced induction. Those Supercharged Series III engines (L32) crank, but you have an NA L26. I believe to swap over everything to get an L32 would be either a donor supercharged engine or all the parts necessary to do what GP guys call a "top swap". The cool thing here is that in the end, it will actually be faster than an OE supercharged engine because you are keeping the higher compression pistons. That will give you about 275 hp and with a tune and a pulley kit probably about 350

If that isn't your style, ZZP has a centrifugal supercharger kit (think belt mounted turbo) that were pretty good, and those were good for about 310 hp

Either way, you may want to get the HD transmission out of a supercharged car for reliability purposes, particularly if you are going above 300 hp

This section is going to be the spicy stuff. An Intercooler will reduce intake air temps and allow for a denser charge. So add about 100 hp to those boosted numbers earlier. Not enough? Add an E 85 kit (much higher octane than 91/93 premium gas for about 40 more. Much more than that, though, and you will have to start bottom end work as forged internals would be necessary and a cam would be ideal. But if you wanna go crazy, do it. The Series III heads breathe pretty well, but if you're going all out, port and polish the heads with bigger valves and stronger springs. If youre going balls out, top swap with new internals and throw the centrifugal charger with an intercooler on it. Thats good for 700+HP, but you will need a beefier torque converter and a fully built trans. Basically, the only thing past that is nitrous amd I don't know how those engines like the juice

Modifying a car can be as simple or as complex as you make it. From the most basic wheels/tires and suspension upgrades to a street legal race car, almost anything is possible. My biggest piece of advice would be to sit down and make a plan for exactly what you want to do so you are not replacing parts you already spent money on upgrading. For example, if you are going to "top swap" your GP, you shouldn't go and get a set of upgraded coil packs for your NA motor as you will be replacing them down the line with the Supercharged parts anyway. That plan will save you hundreds, if not thousands of dollars. Other than that, do what you want and try to learn how to do what you can by yourself. A significant portion of building a car is labor, so help yourself out wherever you can and save money there, too. That being said, know when you need to turn it over to a professional. The only other things to remember are don't make your car the sole focus in life and have fun. If you need help, reach out here cuz there a million bored mechanics that use this site daily. Good luck