What Can I do?

I have a 2007 Honda Rancher 400AT and I wanted to do a few upgrades to it and wanted some opinions. Its been a good quad for me but it does lack power. I put the K&N air filter on it and jet kit but it actually ran worse then stock. The engine used to surge at about mid-top end and I found that the K&N filter chocked the engine off more then the stock filter when oiled. Clean the filter oil out of it and let it dry and it ran great. I do have a outwears pre filter on it but with oil it is just too restrictive. I was just wondering what i can do to give it that little extra. I am putting MudLites on it but am not sure it I have the power to turn them since I am a bigger guy(about280lbs). I have seen clutch kits for it in Dennis Kirk but how does that work with no belts and such? Also, what can I do for suspension upgrades? I just want a little better ride but can't seem to find and shocks to fit it.:sad: