Emann0007

PI= performance Improved, heads, the ones that come on the 99+ GT's if I am not mistaken... I believe they have a different more efficient intake as well.

Monty

THe pi swap. Is swaping out your stock heads, cams and intake manifold to the better flowing 99-o4 items.

StangTangGT

yea unless you want to supercharge it then you would be best to stay with the lower compression of the earlier heads. but if not then go straight to the ultimate bolt on for our cars, not the small 5-10 hp bolt ons. but you need to have a better flowing intake and exhaust either way as your first mods. but skip the cai and pullies etc... go with gears definitely and if your going to get new heads then you might as well order some better n/a cams as well. and get a cheap 40$ fender mount intake for your car off of ebay. they work miracles for the price.