[Hectic]

A good inner barrel and hop up rubber are good investment.
As far as the hoa setup youll want a regulator at the bottle then youll want another small regulator (one that goes between 10-200psi) between the first regulator and the magazine then you set the main regulator to 190 or 200 psi then you use the smaller regulator to adjust the psi till you get the right fps around 425 or so. Thatll give you a buffer for temprature changes and such.
Be sure to keep and eye on the mini regilator for psi changes (say its set at 120 and after a few hours the sun comes out and it gets warm it may climb a bit so lower it back to 120. Putting a small mark with marker will let you know exactly where to set it for the right fps. Also a tip when you set the lil reg turn the big one down so its only 10 or 20 psi higher thatll give you moreof a safety buffer if the mini reg fails you wont have a huge raise in fps.
Main thing is always check the small regulator to be sure it stays set at the correct psi.
And dont go turnin up the psi once the gake starts thinkin itll give you more range or something cause ot really wont and if you wind up hurting sommone you wont be playin with that group again and it wont ne long befor the community finds out and then you wont play much of anyplace.