Would love to test it on an engine with 8 EGT's, but looking at the overhead shot of both makes it seem like the mixture distribution wouldn't be as even on the 4500 flange version, a disproportionate amount of the throttle blade looks to favor 1, 7, 2 and 8. I'd expect cylinder to cylinder variation that would be partially resolved with the smaller opening. With EFI you can fix some of that distribution with individual cylinder timing and fuel trims, but you can't fix lower output from less air physically in the cylinder. 440-3 experience here. #1 and #2 were always the leanest, #3 was a little leaner than the remainder. I had the intake ported and the guy who did it dimpled the runners on #1 and #2, this helped. He had also flowed a -2 (not mine) with and without the 4150/4500 adapter, IIRC he said it lost 10 -12 cfm per port with the adapter. For info we swapped to a 3x and picked up 2 tenths, 25hp on an old 750hp 528 combo.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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