I have just acquired a TRF416WE and can fit 5400, 45C lipos no problem, the bulkhead and top deck is even perfectly shaped for using 4mm connectors without a problem.
The 415 is a bit difficult for lipo as the rear bulkhead is shaped to hold nimh securely, the way round this is of course to 'file' the rounded edges off the bulkhead.
I have also had no problems fitting larger lipos in an MI3 or my HB Cyclone WCE.
Corally RDX and AE TC5 were useless at securing lipos mainly due to the older design battery bars rather than using tape to hold the cells in place.
Of the cars I have mentioned, I can fully recommend the TRF416WE, best car I have used in over 20 years of racing RC Cars.
