I have just returned from WMSS and my car sports a shiny new DI cassette.
Upon arrival a number of tests were performed on various bits of the vacuum system. The one-way walve on the crankcase breather hose was found to be faulty. Apparently this is bad although and they explained why but I am still not sure it makes sense.
Everything else was found to be ok, although they strongly advised me to change the dump valve for a more substantial version. Elkparts sell Forge valves so I may well be purchasing one soon.
The DI was then swapped for a new unit, new plugs fitted, and I took the car for a drive.
Found a nice bit of dual-carriageway and proceeded to evaluate the performance. The car felt good with possibly more boost higher up. Very hard to tell though as everything goes by so quickly.
On return to WMSS (after getting lost) I purchased the parts. They said I could return the DI cassette if I felt it made no difference.
Car felt good on the drive home. MPG at 70mph seemed improved over recent drives. Perhaps this is a placebo effect or maybe a new DI helps?
Still got my brakes to sort out – have had a recommendation for Black Diamond disks so shall check those out.