The exhaust is a good place to start, I prefer the X pipe over the H pipe simply because with the X pipe you make more horsepower at the top end. With the H pipe you gain more tourqe at the low end. And with the Cobras you can put a 4.10 or even better a 4.30 rear end gear to make up for the less amount of tourqe you get from the X.
I suggest a cold air kit with a k&n air filter, along with the steeda timing adjuster, pulleys, many people use the steeda pulleys because the crank pulley uses it's own dampner for saftey reasons.
Hope I helped, Will
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98Cobra-3.73,Offroad
Xpipe,Flowmasters,Mac Cold air,SteedaTiming Adjuster17deg,Autometer Shiftlight,NittoDragRadials