How much are you looking to spend? You can make an intake/filter setup yourself for around $150 if you have the ability. With the intake, you can then add a free flowing exhaust and get a little more power. You will need to adjust the mapping for the correct mixture, so throw in a PC5. This will all run you around $1000. As far as clutching, the hot set up is a STI primary and secondary. Or, the Airdam set up with is about the same. This is going to run $2000 +, so its not cheap, and to be honest, it would be a waste of money for a fairly stock engine. I hate to send you elsewhere, but all of this has been hashed and re-hashed on the Commander forums. Just google search Commander forums as I dont want to link to another web site off of this one. Probably not good etiquette.
Here is the thing and I know you said you are not going to be racing. Stock, the 800 Commander is over 10hp more than its closest comp, the RZR 800, and WAY more than a Teryx and Rhino. I see you have a base model and its only around 150lbs heavier than a RZR. If you did a bed delete, you would be within 50lbs of the RZR with over 10 more HP. That and the fact that you have a trailing arm suspension over the RZR and you can get more HP if you really want it. I dont understand why people arent racing these in the Production 850 classes out West. With a LT suspension and some tuning, you have a car that should lay waste to everything else out there in that class. Easily!
I know I didnt really answer your question, but to be honest, there really isnt cheap power to be had with these engines. You might read there is, but thats just advertising. Good luck and have fun.