The return line must be at least as big as the supply line, minimum. Otherwise the return hose becomes the restriction. And if you are using a high GPH for application pump, it should be one size larger.
I've heard this before, but many don't agree w/ this. One of the engineers at Aeromotive recommended the -10 feed and -8 return on my car and it works flawlessly. Many factory EFI applications use a smaller return than feed also.
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
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