Mr tony, does the sidepipe conversion involves the fitting of brand new wings? If it does, then surely your old wings should worth at least £4-500 each, new wings from MMC cost £800....
Err and don't I know it! 3 months after picking up my aero I damaged the front of the car in a 5mpg shunt. Purely superficial damage. Took me a long long time to get new wings. The S1 wings were completely out of stock at the time.
Being an S1 - to get wings with siddepipe holes you'd need GTN wings, which given they only made 12 GTN's, would mean they would probably be made of unobtaneum..
This is probably the main thing that puts me off this kind of update - once you ahve CUSTOM bodywork, let alone low volume, any bodywork issue / dent etc becomes a major pain the the arse...
Do like the SLR idea on the sidepipes - great thinking!