If anyone's considering this in the UK, I've just had the work completed at
Grinspeed Motorsport in Leyland and would highly recommend both this company and MFactory.
All queries (both to MFactory and Grinspeed) were answered pretty much immediately and I couldn't have asked for more when the work was being completed.
Stevie (the owner of Grinspeed) was willing to meet me out of hours to arrange delivery and collection and whilst the work was being completed I was sent ongoing emails and pictures showing how everything was going. At collection, Stevie wouldn't take payment until I'd fully tested the car and was adamant I'd take it for a good run and was 200% happy before letting it go.
Overall a great experience.
Here's the contact details for Stevie and Grinspeed:-
http://www.grinspeed.co.uk/contact/