Thanks for the quick response guys! It's a 1975 280z with the short block from a 92 TBI and 906 vortec heads with a mild port and polish. The cam is roller with a .450 intake and .480 exhaust. It has a t56 6spd from an Lt1 camaro. Summit 4bb carb with vac secondary. The rear is 3.545. Car weigh about 2800lbs. The car is very fun to drive but I can't help to think that my exhaust is not efficient. Oh... it's a 5.7 and I shift around 5.5-6k