I know others will tell you to put a clutch kit in it. Have you had it in the mud yet? I've got 27's on my bone stock Rhino and have not had any issues in mud. Just pull it into low range and go. Maybe I'm not going to right places but I've never had the wheels stop spinning because the clutch wasn't right.
I suggest once you put a pipe on , its time for a fuel controller! If you went to 28" tires a clutch kit would have to be done.If you have the proper combination of pipe, intake, and fuel controller etc. ( get it on a dyno and away you go)
a clutch kit helps any rhino, gives you more bottom end grunt, as well as mid and top end improvements, if your looking for a bit more on the top you can change out a secondary sheave with a 700 grizzly one and you will get a more top end just a little trick:d:d:d