Bit of an update, I had an APR stage 1 tune done at CLP Automotive in Sheffield last week, mine was the first 7.5 R that they'd had in for the tune, and apparently APR had just released a brand new file that week so they were excited to see the results. Here's the post on their Facebook page -
It made 373 BHP and nearly 400 lb/ft of torque, which was a bit surprising considering this was supposed to be the 'low torque' version of the APR map! with the car making 320bhp stock, I can only think that the CLP rollers is slightly on the generous side.
The car feels amazing now, so so much power and overtaking other cars makes them look like they're standing still, I'm sure it's the same for the pre-facelift cars too but I'm just over the moon with it now.