Underdrive pullies, highflow exhaust and filter and I think thats about it, I know a while back I read an article about an intertia ring but that doesnt give you more power just increases amount of recipricating mass which in return will give more torque kinda untill you fall below a certain point in the engine rpm range then it will actually cost. For most part your limited unless you go with gears but that doesnt increase power but will help out. Also if for some reason you have a/c which i doubt you can remove the compressor that frees up drag, and will also save you some weight. Also along with weight if you have a hard top switch to soft. I know that my 2.5 perfomed a lot better with the soft top. Also git rid of the back seat, carpet etc it doesnt sound like a lot but every bit counts