5.4 3v will stand 12psi. Thats the limit. 12psi with supporting mods and a very good tune will get you in the 475rwhp range safely. Cams and an electric water pump will take you all the way to 500rwhp which is the absolute max on a stock rotating assembly. The stock rods are rated at 400 flywheel hp @ 6000rpms. The way to make more power like we are talking about is to bring the redline down. The harder you push the motor the lower you have to go. I'm at 5600 now. Keep in mind 475rwhp /.75 = 633 flywheel hp. That puts you 133hp past the rating. So extreme care in tuning is needed. The stock tranny equipped with a valve body and a tuner who understands it's limits will hold up fine. However very few tuners understand these needs and you'll smoke the stock trans in a heartbeat even on 8psi. 8-10psi is a good level for the motors. Plenty of power and not quite the expense of higher levels. I added a fuel system ($1400) to be safe or safer when I installed the 10psi kit. The stock fuel pump can handle it but it will live a much shorter life and if it has a weak moment at WOT you're gonna toast the motor. At 10psi you also need to invest in LT's and a good exhaust system to keep the heat under control. The stock valves will only handle 1600 degrees for a few seconds. It is easy to see those temps with a stock exhaust manifold or a poor flowing system.
^ thanks for the tips. Someday I'd like to get a Whipple and maybe be able to keep up with all these new motors lol.
