i'm not pro so i just bought a dye ultralight barrrel with a .692 back to shoot basically any paint just fine. also NDZ back cap or the Dye aluminum one are both great... Next i'd get NDZ slik trigger or if your waiting for UL frame i guess u could just use stock trigger, I'm not plannin on an UL frame for a while so I put a slik trigger on. That's about all that really needs (or has) upgrades atm besides aluminum eye covers and feednecks. Also if you like eyes that put off like they are like 30 bucks but i haven't bothered with those yet. (although i'd try and get blue cause all my gear is black/blue and my gun is all black atm.
So if it's all the player and the gun doesn't really matter... how come none of the pro's use a (insert your crappy gun here)?
Proto Matrix Rail
NDZ slik trigger and NDZ feedneck
Shocktech on/off ASA and rail
Dye UL barrel
Dye aluminum back cap
Halo B with rip drive and v35 board
68/4500 Pure Energy HPA with Empire cover