I think its around 140 with slp head stock head is 150Not sure what your after, the stock head is at the limit for super93 octane, So going down some will make it safer. What the comp. in psi on the guage is going to be I'm not sure.
I think the stock head is something like 13-1, so getting down to 12-1 would be a good area, may even be a little faster on top end, but a little slower in the midrange pull.[/b]