Would anyone like to guess why my power is dropping off abruptly? Spark, fuel and boost are where they should be. My tuner suggested possibly needing valve springs. I have a stock bottom end, stock heads/cams, psr, longtubes and vortech ti trim sc. The lower hp graph is with a 3.6 pulley. The higher hp is with a 2.8 and a wastegate set at 10psi. 1999 Cobra. Notice the nosedive at ~5500 rpms. I've attached a datalog from a street pull.