The car you linked to Richard has the factory developed ECU upgrade to cure the rev hang and give power increase as with John's Brooklands. It also has the AR rear exit sports exhaust option although not sure what further power increase if any, that would give. I can only tell you the AR side exit sports exhausts mine has doesn't diminish it
Sounds like an excellent opportunity to join John's Brooklands register for the lucky new owner and at a fair price.
