BARREL FIRST. all of the paintball experts say that a barrel will do the most to your marker in a positive way. As for me, i wouldnt go with the apex i got a J&J edge kit which is sweet. as for the palmers stabilizer i think it is way too expensive and would rather get an expansion chamber instead. HPA i think would be last. It is just too expensive for my taste and not necessary if you got the reg i think. but these are just my veiws. I still dont think the reg is worth it what does it actually increase other than concistency which the expansion chamber can do. Also i would like to hear about the internals i was considering buying a delrin star fire bolt.