Yeah i vote the Palmer Regulator, although I dont have one, yet, i sure wish i did. My first, (and only ) upgrade was the Apex Barrel, I love the barrel although when snipering, if the other person has any chance of seeing you move then you cant really turn the end of the barrel or even adjust the ramp without the other person seeing you, so unless you know where someone is and they cant see you, the Apex barrel is just any other aftermarket barrel. I have shot over 4,000 shots through my Apex and not a single ball has broken so if you are looking at an APEX, you are buying a good barrel. but really, I would buy the Palmer Regulator first no doubt. and also, I would just leave the internals alone, maybe you could polish the inside but other than that, the stock Power tube seems to show just as much performance, or more for some other aftermarket powertubes. Polishing your internals reduces wear, and increases velocity by about 10 fps, give or take depending on quality of polishing, I will be polishing my A5 the day after tomorrow.