HasselZ28

I know that these questions have been asked a million times before but I just have a few. After I put the headers on I will be complete "bolt on" car, I did by NGK TR55's what do you guy's recommend me to gap those at? Also, is there any advice on doing the header install I bought Pacesetter LT w/ ORY in my 2002 Z28 Auto. And if anyone can give me a good prediction on what kinda of HP numbers they think I'm looking at. My mods FRA, Whisper Lid, Descreened MAF, PP TB, Pacesetter LT, Hooker Catback, 3.73 gears. Thanks all help appreciated!