I had several of the Nitro Hawks and the brakes can be adjusted to not lock up but it takes a lot of playing with the servo adjustments. a spring or piece of fuel tubing on the linkage to absorb some of the pressure from the servo on initial application would work. The brake setup is similar to the old Brezinski setup for the GT if I remember right. I always burnt up the brake arm since it's just plastic against the steel clutch bell. I think some gasket material glued to the contact area of the arm would help make it last longer and may smooth out the braking as well. The brake arm applies pressure to the clutch bell. The problem with more power for that truck is the crank is a goofy length compared to most engines (longer). The flywheel and clutch bell are turned around backwards from the normal setup. If you try to install a regular crank engine the clutch bell teeth won't line up with the spur gear. You would have to move the engine back to make it line up which will require either re-drilling the chassis to move the existing mounts back or using different mounts.