Receiver cut out - BEC or HRS issue?

[s22jgs]

heres a strange one for you im having trouble resolving.

In my mardave i have the following:

2600mah 20C LiPo
mTroniks Storm X ESC (from modelsport)
HPI 20T Saturn motor
Spektrum SR3000 HRS Receiver

All seems to run ok, but when i steer anything near to track speed steering, the receiver cuts out.

I've come to the conclusing that this must either be an issue with the BEC lead power from ESC to receiver, or the ESC doesnt like the HRS Spektrum.

Personally i think its the BEC, but how to i get round this issue. The ESC is all pre soldered and closed, so i cant even add a power cap can i?

Slightly miffed with this one now.

Any ideas?