The 1100 is limited by the h-stat so increasing the top speed is tough to do... I have heard you can trun the pump pressure up to close to 5000psi but any dealer wont just do that for you. Our 1100 is a commercial work horse with a 1000lb soil sampler rig mounted in the box. We have put 30" ITP mud tires on to get through the messy stuff and have found that the Kubota is super sensitve to carrying the extra wieght and the extra power require to turn the big luggy tires. High range does not even work for us anymore due to the load and big tires, I have told out employees not to use high because the fluid will bypass and its hard on the HStat. Kubota has looked at it and says this is a normal limitation.
Our top speed with our setup is 17 mph on a flat gravel road. High range is no faster, and we find ourselves stuck in low (10mph) most of the time.
The beast is really heavy and will get stuck in snow if you high center the frame (even just a bit). Having a Winch and cell phone is a must. Last time I was stuck in a snow bank, the 1100 couldnt even spin the tires in low. (A little dissapointing) The difflock makes a huge differnce in snow as long as you keep your spped up. I am ordering a v plow so i can travel in deeper snow to get to our remote remediation sites. Keep you momentum up whenever you can, or you'll be stuck or finding yourself stoping to shift into low range.
Anyone had good luck with a turbo? I'll bet you could get the tires to spin with one.