Years ago, sealing the carb to the hood. This was worth 1-3mph and +.1 in ET....Nobody believes me on that, but it is true.

For me this 2019, it was upgraded rocker arms and push rods....Was wrecking pushrods and rockers like candy at .680 lift with our new 400/512 combo. Went to Comp SS rockers with more offset on the intakes, and Manton series 5 extreme push rods....Wow...Night and day difference. Never even took the valve covers off this year.

Was using the 440source rockers and pushrods, which worked well for 6 years, but now we are in the low 6's in the 1/8th and finding we needed better parts.

Also, the other biggest gain we netted was working with Thumper on the carb setup and I ported the crap out of the manifold....netted .22 total and 2mph

Last years big gain was calling Hoosier and getting the right slicks for our car....How about a 1.31 60ft!

A while before that, sealed the carb to the hood.....

Things that netted us nothing, but we like anyways:
Firecore wires over Procomp generic ones
Light weight crank....6lbs lighter
Switching from a 440/512 to 400/512
increasing compression from 10.75 to 13
Front facing hood scoop
Trans brake
PPP shifter
Magnefuel 500 pump over a 275