I personally would suggest the mud runners if not go with the mudbugs. just my .02

 

These big tires must slow your bike down alot?

 

Going to a 26", you don't notice much difference at all. Moving on up to a 27" or 28", you would probably notice it more. The Rubi has plenty of power to handle it though.

 

One thing to consider is the weight of the tire and the factors of inertia. A heavy tire like a heavy flywheel takes longer to rise to a given speed than a lighter tire will. So a heavier tire with a larger diameter will have an effect on the acceleration of any given quad.