[Stang_Crazy]

The 8psi Vortech is the S-trim. The 6psi kit is the A-Trim (I think it's called the SQ now, right?). The S-trim has more room to grow (higher max boost) and will flow more cfm at the same boost level as the A-trim.

Edit: I had to tap the oil pan for my NOVI 1000 and it was one of the easiest things I have ever done. Don't let it scare you away from the NOVI 1000 or 2000. It's not as bad or as hard as it sounds.