Good for you on paying attention to this. When some of the original batch of hot clones came out, guys were playing indoors with them. A buddy of mine left a game with 3 BBs embedded in his back....nasty stuff.
Stick a M90 rated spring (90 meters/sec = ~300fps) in it. For a lot of CQB there's really no need for much more and it'll just plain hurt your friends. A lot of times you end up in a tight spot with shots really close up and it's nice to know in the back of your mind that you're not going to be dishing out batches of bloody welts.
Modify make great springs...their S90 spring would be a good one. Depending on your setup, it'd give anywhere between 300-340fps w/0.20's. It's a wide range of FPS...and that's another good reason to aim lower than the maximum listed limit.
Best of luck.