They did both. I forgot to ask what gap they did though. They did comment that the MSD box did contribute the nice gains in performance perhapse even as much as 20 hp. They ended up going with a 3 inch pulley to get the boost we were after. The average afr was 11.3. The peak AFR was at the upper end of the rpm range and was 12.3. They said that it was a little high but still in the safe range (lower than 12.5). They may still do a little tuning to bring it down at the upper rpm's.