I had a Carter 6903 on my 440 with stealth heads and a similar size cam, and was dropping to 3 PSI at WOT even in 1st gear. Also had crappy Hush Thrush mufflers I originally bought just to keep it quiet temporarily when the motor was fresh. I put an Aeromotive electric on and 20 inch cash Ultra Flos. The car is quieter, way more responsive, and feels like it picked up 50-100 hp.