well the lack of power and throttle response is probably your MAF, i have heard of many occasions of the 2.0 MAF going back, they're cheap, replace it, and the cam sensor youw ould have to get professionally checked to make sure its okay.

and supersport is better than JOM (in my opinion of course)... if you're just lookin to get low, not necessarilly handling or for track use, i say just go with whats cheaper. if you're looking for a track set, i recommend H&R or Ground Control