List Performance/suspension Upgrades

Okay, I seen a couple different things on ebay, for around 5-10$ one of them hooked on your intake sensor, and the other one hooked on the ECU. That was probably around 15-30hp. And of course, cold air intake, and exhaust are a given. For suspension, I seen some coilover's for only 39$ which I thought was too good to believe. I dunno about that. Well, is this stuff worth getting? And also, I wanna make my sunfire as powerful as possible. I was just wondering where I can begin. I know of a supercharger, but really nothing else. And the supercharger was like 4500$$$ which I thought was a bit much. But really, this is all gonna be done over time, so money isnt really an issue. So could someone please help me find out some more stuff I could do to the engine? I'm a complete newb as this kinda stuff, and I've looked all over the internet (apparently not in the right places) and cant find hardly anything.

Thanks for any replies.

i dont own or kno much about sunfires, but i kno them chips are shit, as you read the info on them you notice it says UP TO 30hp, i put one on a bronco, it actually made it slower in the 1/4 mile, you could begin with an exhaust, and an intake, you could also get your computer reprogramed, i wouls start saving for the supercharger if you plan on keeping the car for a long time