Depends on track prep. If not prepped we'll I do best with 15psi with 672 RWHP and 710 RWT. With a prepped track I run 18.5psi. I get best traction when I do my burnout in Drive and as soon as it's going in second I burn out of the box and stage at about 1900 rpm. When I do a long burnout in box I can't bring the rpms up beyond a 1000 without traction loss. I run low to mid 10's and that's on 18" rims for my drag pack. Thinking about going to my regular 20" rims with 555's on them, because first gear is a little short and think I can probably leave harder on a taller ratio..