black/blue 693 the freak barrel kit, a sp on/off valve, sp gripz and a feed neck, 47psi 3k, and a empire reloader sound activated.
Well i would say the none..but if you want your ion to kick ass like a shocker. Then you should upgrade your board, blade trigger, bolt, better feedneck, halo b hopper, a cp on/off valve (or other on/off valve), a black heart board or the new pb vantage board (coming soon), Qev, and a 45k 68 psi. Remember its not necessary to do all these upgrades because the stock ion work good for me or better yet buy the smart parts ion pro on any a few stores..is very rare to find them.
EVERYTHING!! this gun performs like a dm4 or a proto matrix or some times better.
Seeing the light and changing modes of fire that's about it..
This gun is basically a stock ion with an s rail, new feed, freak jr, and on off, and a new grip. This gun is great for mid to pro level players because it is quick, basic, simple, and not that complicated. If you like the ion spend the xtra 60 bucks and get a pro.
I would recommend you guys to get this gun.. its really easy to take a part, and the performance is really good and so far i have not found any problems with this gun. except me not knowing how to turn it on..ROFLMAO!! im a nub i know but yeah this gun is really good..THIS GUN IS THE BOMB!!