loss of high rpm powerlast

bob brady

3 black cars
last summer my car's dyno pull produced 446 rwhp and 633 rwt. this winter i added 60 lb injectors, precision slic, beefed up transmission, and et streets. recently i had a dyno pull that produced 380 rwhp and 479 rwt. technician said the power dropped off at 4900 rpm, yet last years run pulled to 5750!! i doubt it's the valve springs because i have only driven the car 200 to 300 miles. on the road at wot it seems to strain at the end of second, begging for a shift! when it finally does hit third, it pulls much stronger, same as it does in the beginning of second! any ideas?

dank GN

BlackArts Automotive (661)993-8277
What valve springs do you have ? Springs lose pressure after the first couple heat cycles . Do you know how much pressure you have on the seat? Open?