There are some that cut the runner length shorter to raise the rpm band but I am not sure there is much to be gained there on a street engine.
Engine Masters did a dyno of the "super duper" modified kegger that UTAwesome performance works over to the tune of $700 bucks to buy one. With a small cam (218 @ .050 IIRC) it only made 10-15 more torque and hp than the stock kegger.
Probably not the best bang for the buck at least with that small cam. Maybe it is better with a longer duration cam I dunno.
