I know in my injected 408 Chrysler Wedge, 10% gave me a .10 in the 1/4 mi. and 18% gave me 2 .10's, 10% was no change to anything, timing, fuel jetting or converter. That 18% wanted a tad more fuel and it was pushing the converter pretty hard. 14.2:1 compression Ross pistons, GRP rods, steel 383 crank, indexed and cut down for SBC big end, Indy 440-1C heads, Indy stack injection that had been heavily modified (from Indy, it would either idle or run flat out, wouldn't do both) MSD 7AL-3 box with the MSD 2 amp coil.