We have some very interesting products in the pipe line to transform the brakes on the Punisher/Destroyer. Hopefully these projects will be tested and in production very soon
Some sound advice being given too. On my brakes at the moment I have a rhino 4, it's well worth fitting a large scale servo for brake duties, the smaller servos, as was mentioned, do seem to lack the holding power of the big servo's.
The only thing you need to fit a big servo for throttle and brake is the brace that comes with FTX 7538 Servo Mount Set.
To be honest I've found the brakes to be 'ok' as standard. But, they do take a little time to set up and the do go out of whack pretty quick and need resetting.
A solution wil be found though
Nige