The 2-piston brakes on the Biktrix were not meeting my expectations. They were also real load on very low speed braking, like walking the bike down a steep hill. I decided I needed an upgrade so I bought so I bought Zoom 4-piston brakes off Amazon. I ended up just using the calipers. The tube ends were a bit different so I had to do some work there to adapt them for my lines. My front brake line had been damaged, and it is all exposed so I did use the front brake line that came in the kit. The rear brake line goes through the frame and motor area and it would be a much bigger job to replace that so I retained the line and modified the caliper end to fit the new caliper. The rear brake line is also in very good condition. I did not use the handle/cylinder ends from the new kit, instead retaining the Biktrix units. The switch in the handles was not directly compatible with my bike and my original handle/cylinders are in good condition. I have a nice firm brake feel even though the calipers are larger volume.
I bled them and went for a road test. After breaking them in, they improved stopping power significantly.
Biktrix offers a Magura MT5e with Bafang HiGo 2-Pin Connector upgrade for $320 ($20 more with the electrical adapters that are needed). The Zoom HB876E kit I bought cost $85.
I also upgraded the rotors a week later. My original rotors with over 2,000 miles on them were glazed. These are 180mm rotors and I considered upgrading to 203mm rotors but I was not real comfortable with the adapters that are needed for this. Bike rotors are inexpensive (<$10/each). The photo below shows the original rotor still installed, and the new rotor for comparison.
