azjay wrote on 12/31/69 at 16:00:03:we run a 152.5 main, 1/2 spacer, #55 pilot, and we're at +165'. we also ran a 155 main, 2/3 spacer, #55 pilot, with good results. i attempted to pick up some gas mileage by downsizing the main jet, i dont think it made a lot of difference, because the mid range (most riding) was compensated by raising the needle.
Remember that you will not see any difference in the main jet size except in the 3/4-full throttle range.
Needle ... 1/4-3/4 throttle range
Pilot ....idle to 1/4 throttle range
There is some overlap of course, but that is the basics of it.