Vac off 39-40 at idle is fine. Pull the vac line off the manifold leading to the regulator while at idle and confirm gauge is at 39-40 and your set. 19's are good untill your heads are upgraded, or you go to nitrous, or any serious mod then you will best be looking for a new MAF calibrated for 24pound injetors and the 24's, exhaust with stock heads/ported stock heads, and standard bolt-ons...19's will be more than enough.