barrel i would say is the first thing you should get
if you like double triggers then get one of them
rocket cocks are nice but they dont help anything just make no moving parts
drop forward will move your tank down farther and make it so u can use it like a stock on ur sholder
HPA will make your shots more consitant
xchamber only if you use CO2 it helps make it a gas
e-bolt will make your gun ele and fire faster
thats a few ups nothing specific
hit me up on AIM if you want more info
LP kit i would recommend this if you get HPA
i dont know ur prefrences...but i have a sub-zero exp, dead on drop wit on/off, progressive and tear drop(tear drop much better), 12v revy, double trig, sticky grip, and bout 5 20 oztanks....and thats just my 98....anyway those r my suggestions but dont hold me to it cuz ur not me and might have differnt prefrences...
i couldnt tell u want u want but i can tell u what i have on my gun and so u have a better idea of what u could get so here it goes.....
12v revy
alumeunm internels
dead on pro blade drop
14 in tear drop
12 in progressive
8 stage sub zero exp
3 way stock
double trig
that gta sight rail(no sight yet)
hope this helps