has anyone used one of these cams before..If so did it make a noticable diffrence on performance or milage?I have a 97 2.5 with a banks header and a k&n air filter,e.fan.Im in the process of flushing my motor(lifter noise) and if i have to replace the lifters i woundnt mind the extra work to replace the camshaft if the hesco 1 makes a good diffrence.Any opinions or advice would be greatly appreciated.chris