i talked to the people at hpi today and i am on the list for some new a arms probably be here in a couple of weeks.
they up graded the front a arms but did not change the back a arms they are the same old ones that came with the front a arms.
the rear a arms can be drilled and modified to fit the front and they will work.
i drilled two and they are on my hellfire now haven't tried then on any serious jumps yet but they work fine going around a flat parking lot while brakeing ion a nova rossie rex 528.
insane power.
Dirby.