The pinch piont /or the push rod casting boss in the intake runner.you will see a area in the port where the push rod runs close to,it is cast into the port wall,by running ofset rockers and filling this area in with weld or by press fitting a tube into it,you can regrind the port to make it look like no pinch area was ever there at all.This area can be grinded down to about .080 thickness and no more and will be safe,and will increase the flow with big effects.Mrmopartech