Trigg

First off im Trigg I have spent most of my time in the 3.8 section because my first car was a 3.8 lol. But as time has progressed I have picked up a 1998 GT Automatic with 130K miles. Iv already done some minor stuff to her. I got a MAC CAI, 3.53 gears,O/R H-pipe with 2 chamber Flows,Steeda billet switch covers, 7.5mm T-Body "came with it", cant remember the name but its the none plastic upper intake that also came with it.

Im not to familiar with the 98 4.6 engine or any model 4.6 to be honest kinda new to them so bare with me. I hear everyone talking about getting PI heads, now r those the heads off the 2000-2004 GT? Also will cobra heads fit or r they to big? I read something about SVO heads being better then PI's, but I thought the SVO was a 4 banger. Just need alil basic info on the engine and what kind of power they can hold. The only problem i have is starting it after is sits for longer then 20mins. Its like the fuel pump doesnt hold the pressure or something. Thanks for the input fellas.