A lot more space from manifolds and especially headers as well!
I've had a PMGR for about a decade now. Never regretted making the update.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.