the palmer regulator is a great addition to your marker for sure. but i would only put it as #1 if your running CO2 through it. if you are going to start out with HPA (which most dont) i would upgrade other areas first. but if you run CO2, the palmer is going to be your best friend as far as upgrades go.

on that note of CO2, if you bought your A-5 with full auto, i would try and upgrade to HPA as soon as possible, just because ive seen it so many times where people will open the A-5 all the way up on CO2 and end with freezer burns or something because their tank got so cold from the expansion.

but like it was said before, its really all up to you.