Date Added: Friday 18 December, 2015
I fitted one to my 2005 NC drivers seat and it's fixed the issue.
The belt is still a little slow to retract, but it retracts, which it didn't do before.
It's held in place with one phillips screw, and takes about 1 miniute to change.
Now waiting for MX5 parts to get the passenger side in stock, so I can the other side.
Rating: [5 of 5 Stars!]