I did use the spring kit and upped my fuel pressure with the red regulators that were provided with the procharger kit .

I have since had procharger give me a 3rd size pulley smaller in diameter and I am know at roughly 6.7 - 7lbs of boost on my 496 ho kit .. I also had major work done to the motors from Gellner Engineering with the help of Dean and Dyno Steve we had Dustin at whipple recalibrate the computors (and yes the computors will cause a lean issue)to the specs we gave him. We upped stock rev limitations to 6000 from 5400 and changed all the air fuel ratio eveery 500 rpm
also changed the injectors which procharger included

If you have any ? email me toc [email protected] or call Dean 1 440 476 3558