wills98cobra

what are pi heads (the difference between them and factory) and where can i get them?

II 98 GT II

PI heads stand for Power Improved. The 96-98 GT's all had crappy intake manifolds and heads(didn't flow well). The new edge GT's (99-04) had the PI heads, intake, etc. and they were more powerful. People with NPI (non power improved) stangs, such as myself, often will do PI swaps to improve power. You can buy PI swap kits from a number of places, or you can just search for used parts.

The idea of a PI swap is only an issue for owners of 96-98 mustang GT's. If you have a cobra, like your name says, this isn't a topic that is relevant to you.

droptoppony

if you have a 98 Cobra then the heads you want to look for are 99/01 Cobra-Mach 1 4V heads (C) /Intake or 03/04 Cobra 4V heads with a 99/01 Cobra Intake.

The Heads you have (B) are not bad when ported and your intake can also be ported or extrude honed. Cams are also i nice bump for you...