We do not have a pro mod, however with a stiff wall tire in most cases you need to run 6lbs of air and up. We run the good year 2078's on our 7 second beretta and I usually run 7-9lbs. Anything less and it will shake like no other. On the other hand a soft sidewall in most cases are designed to wrinkle and work with 4-6lbs of air.
We ran 4.75lbs in a 2400# car runnin [email protected] or [email protected] but obviously each tire is different based on sidewall, rollout etc.. I've spoke w/ several guys runnin more pressure for consistancy but sometimes the track won't let ya. Test, test, & more test for best results. GL