Been out and about the River Fal today driving, if this is being run at full power from Redruth, there are areas that are reached by the D1 National, BBC and Cornwall muxes which the SD one isn't penetrating. Hopefully this might indicate that the mux is still in test mode and isn't at Full Power yet.
SDL from Redruth should be 2kW. D1 is rated at 1.32kW...
Steady, it is indeed licenced for a Maximum ERP of 1.995kW (aka 33 dBW), but with 14-18dB reductions in a south and westerly directions