i ran the stock box with my 18g. teh Perrin SRI that i tried next ran leaner.
when i was getting tuned the SRI was ausing a lean spot from ~3000rpm to 4000rpm at about 13:1 when the target was 11.5 and was still lean by 1AFR by redline. the tuner (who has 13 years experience) tried throwing fuel at it as well as adjusting calibrating the MAF, but still the same results.
i was able to borrow a friends Cobb SF intake, and the afrs went back to the targets.