i put a set of hc's in a 01 800x . 4.3,11.0,and 8.0 tip.i am running the beige secondary spring @ 21lbs. seems to be running about 8000rpm. my sled pulls great up to 90 mph , but seems to flatten out any suggestions? i am also running a dyno port pipe and silencer with reed spacers and carbon tech reeds. jetted down to 480's and have 1.25" sabers.