My hemi was built specifically to run on 93 pump gas when N/A. On VP 110 fuel it slows down about a tenth in the 1/4 and a little over 1 MPH. I didn't change anything other than the fuel.

CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax