Big tube header vs small tube header on a stroker

At 7000ft last year 1 5/8 headers and running dangerously lean the best run was 11.72@114

This year with tti 1 7/8 and not lean, [email protected] 7000ft da... same everything else.

I'm sure the lean condition didn't help... but almost 6mph and 5 tenths... I dunno.