I disagree, read this------>
http://sn95forums.com/index.php/topic,116.0.html
PI heads are way over-rated. P&P the stock heads from a reputable shop (that way you keep stock compression if you want to throw a little boost at it later), slap a nice Stage 1 or Stage 2 cam in (blower cams for when you do boost it), PI intake (make sure you get the one with the aluminum crossover), bigger TB/Plenum or port the stock ones if on a budget, CAI w/bigger MAF and get it professionally tuned. This along with a full free flowing exhaust will make a huge difference, all without the PI heads.