performance chips/improvements

I want to get a performance chip for my car - 08 g5 gt and I was looking at a surge perf chip/jet performance stage 2?? I have the header on the car - and someone told me I should upgrade the cold air intake- but I'm not sure what the next thing should be?? Don't have too much $$ to spend...I just want to get some extra HP...

what about getting an aftermarket muffler put on, gives you a little bit more horsepower as well as making your car sound like a beast.

and if you get cat back its even more, but that's when it begins getting pricey

thanks...i thought about getting a flow master part,,,but now i'm looking into getting a new car altogether because i broke my warranty with the stuff i did to the car and there is some body damage as well...so i figure i mind as well start over.