The electronics issue is clearly not relatec to a car specific thread. First thing I would check is to see if the rx is HV compatible sine you have an hv sero. Secondly, did you install the bec correctly i.e, removing the red wire from the esc to rx connection? (correct me if im wrong with this guys)
As far as shock, setup is car specific. I wouod lookup the Mugen MBX6E manual for a base setup and work from there....
Doh! looks like the red wire is disconnected. need my eyes checked. lol.
Do you lose throttle and steering respone?
Good luck.