I have ran a pro carbine as my primary for 2 years now. Love it! The best thing you can do for this gun is buy an HPA tank for it. Brings it some consistency and accuracy. Some other things you can easily do if your a little handy is to remove the rear cap and look at the end that was just inside the gun. You will notice an inset in the cap where the spring pin usually sets. Drill through that, then thread the hole you just made. I forget the exact size but whatever size tap seems to fit best will work. Then go to your local hardware store and find a set screw to fit. Best $1.29 I've spent on the gun.
Also: This is tricky if your not use to working on these guns, so beware. I found that even with the homemade RVA, the stock velocity adjuster, and a soft spring from a model 98 sping kit that I could not get the BPS to drop below 290+. So I removed the valve from the gun, then removed the clip from the rear of the valve (not a c-clip, more of a key-ring like fastener). This is made easier if you push in the brass plug with something to remove the pressure from the clip. Once the clip is out, you can remove the guts of the valve. (3 pieces: Brass plug, spring and valve cup/pin). Now, carefully stretch that spring (careful not to bend). Mine bent a little at one end, so I put that end up against the brass plug (not the cup seal, or it may not seal correctly). The goal here is to stretch that spring back out and make it harder for the hammer to release pressure when you pull the trigger. It may be a good idea to measure the spring to make sure you actually do some good. Once your done, replace the o-ring on the brass plug reassemble the valve and re install it. I did this to my gun and was then able to adjust my BPS to a reasonable rate (265~).
What you must know is how man reacts. Weapons change but [the] man who uses them changes not at all. To win battles you do not beat weapons – you beat the soul of man, of the enemy man. (George Patton)