To get the full use of the #4 plate you will need the 4,000 rpm kit and the H. D. valve springs. With the 3,000 rpm set up your truck will pull harder on the upper end but EGT's will be up slightly, with the 4,000 rpm kit the truck will continue to pull past 2,700 all the way to 3,700- 4,000 and you will think you bought a new truck. I cruise at 2,000 around town now and the truck is just loafing. I was very happy with the #4 plate and dynoed at 383HP and there was more left all I needed was more air.
Bruce