I own the on road version, not sure about off road.
@tudordewolf will be able to assist there, as his knowledge about this platform far surpasses mine.
Good luck!
Get an HSP Flying Fish, its one of my most used and best RC nitros.
It tunes idles and runs great.
Just add another approx $50 on top for some parts upgrades which are not that great from factory and thats it.