We won't likely ever see a bolt on kit, I don't think Brutus sales were high enough to cover development and production costs. The change to the Kolher engine for 2015 makes it even less likely, and those engines have unit injection pumps that are not so easy to increase fuel. PPE would be the ones to bug about it, they do kits for the Ranger Diesel.
I followed PPE's instructions to adjust fueling. For their kit they recommend 1.25 turns out on the Rated Fuel Delivery screw. I'm at 1.5 turns out. I went two turns and got lots of black smoke but no noticeable increase in power. I can't get EGT above 850 no matter what I do. There is another adjustment called Torque Fuel Delivery, I'm trying to find more info on that before I mess with it. I suspected possible intake or exhaust restriction so I did a brief test with intake and muffler removed, didn't notice any difference except more noise. At 6-7 psi I should be able to get at least 34 HP, I don't think I'm even close to that.
I've completely eliminated the HP management function from the hydrostatic pump by adding a screw to close the gap between the command lever and pintle lever. It allows me to put maximum load on the engine. From a standing start I can just about stall the engine if I push too hard before the turbo spools up. I've also changed the minimum displacement stop in the hydraulic motor from the stock 9 degrees to 6 degrees. The result is increased top speed in low range of 22 MPH, with the same starting torque. There is a torque reduction after the motor shifts, but the new low range high speed torque is still 50% higher than the stock high range high speed torque. This change also increases the high range speed to something like 48 MPH, but because of the lost torque it makes high range pretty much useless. For my use I am happy to leave it in low range. The final result is that I can do 15 MPH up hills where I could previously only do 10 in low range, and I can do 22 on flats without shifting to high. I'm pretty happy with the way it runs now.
Pictures of the modified command lever and new motor displacement limiter.