Originally Posted by r3dn3ck

the 5.4 2v can realistically in streetable trim hit 360rwhp/tq but that's closing in on about it. After that there's just no flow left in the heads. Reasonable street setups with longtube headers should have little trouble seeing 320rwhp and a little more tq. not having longtubes kills the hp on 2v motors. If you want over about 340-350hp/tq then it's time to go 3v which should be good for up to 400rwhp with a little less tq. 4v motors can easily climb up to 450hp and 380tq but as you might imagine low end tq suffers as upper RPM HP increases. Al Papito made like 540hp in his 5.4L 4v and it jerked the wheels off the ground every time so there is plenty of room for play left in the 5.4 block.

TQ curves will vary by setup but they'll always start pretty strong compared to a 4.6. A really well done NA 4v could easily do the HP numbers a 2v 5.4 does but for TQ... not a chance. It's just not possible thanks to the shorter stroke on the 4.6.

We've only begun to scratch the surface of what's possible on the 5.4 and that's a damned shame. If people wouldn't have stuck their heads in the sand years ago there would have been all kinds of testing and development done already and we'd be talking about how MM&FF only does 5.4 articles instead of how MM&FF only does blower cars (that's kinda a joke but not totally).