IF you drive easy, shift at 4500... cool!! but IF to rap up the engine make 5000 rpm shifts... they will still work at 150K but they are streached and retarding the cam 2-4* !! Dont get confused with 150K on the engine and NOT think it isnt way past time for the bearings and timing chain to be changed!! Esp. if your thinking of running it hard??
Just me.................................
Thumper