I know that headers are recommended with a top swap, But are they absolutely a must have? Or can I get away with U-Bend delete, cooler plugs and possibly 180 degree t-stat. I will be running a 3.8 pully with open cone intake.

The swap will be on a 97 GT. I was reading the topswap thread and it didn't say anything about a PCM. But just to make sure, do I have to get one from a 97 GTP (or anyother PCM for that matter)?