[Super73]

An LQ4 with the following mods should make over 400hp at the crank:

Un-milled Stock Heads
1 7/8 headers -> 3" x-pipe
Stock truck intake -> ported throttle body
Mid/high 23x duration cam

My first set up in the truck was:
Forged 347 bottom end
Stock 243 heads -> 10.25-1 cr
1 3/4 stepped to 1 7/8 headers -> 3" Xpipe
Stock LS6 intake -> stock throttle body
My custom 223/228 108/108 cam

This made 368rwhp through an 80E that has a stock converter, 8" steel wheels with 275/50/15 drag radials.

By no means was it a crazy build, but assuming a low 15% loss through drive train, that was 425ish at the crank. I felt the 80E was closer to 20% meaning 440ish at the crank.