If you have never advance a 509 (108) 4 degree you have no idea how much difference it makes "I do" and it's huge. now if you have a 4200 to 4500 stall you will not see as much but a 2800 to 3000 it's huge!!!
If the motor picked up as much as you are saying with 4* advance i would think it would of faired better with a smaller cam , if the motor picks up when retarded then the motor is teling you the cam is too small , i realise moving ICL around can pose different results , in saying this these cams are tried & tested so the manu will know where this cam will make best power , maybe it was'nt suited for you're application?
Advancing ICL for improved low end power will more oftn than not suffer on the big end.
