Had a chat with Dom at TVR Power this morning.
Following the rolling road session they should be able to fit some new brake pads to the front. These will be the AP racing supplied CP6600D55-DS2500. I guess the extra numbers just show the fitment as well as DS2500 being the compound.
I used DS2500 on the Saab a couple of times and they were very good. They never faded on track despite the high power, fairly high weight, and relatively small disks of the Saab. The TVR has more power, a lot less weight and large brake disks, so they should be fine for hard track driving. In addition, they work fine year round and from cold.
Discussing the brakes Dom also mentioned his thoughts on getting it on a 4-wheel brake tester. Apparently there is one near them. He thought the split should be 75/25 front/rear when static. If I can find the piston diameters for the front/rear brakes then I should be able to calculate the natural bias excluding the valve. The rear has smaller disks (but not by much) and smaller single-piston callipers, but I need to find the exact details.