Sussed out today who these guys are.
They are part of Amber Performance.
The JWR exhausts on ebay are an exhaust that is custom made for the GT4 both 185 and 205.
I was going to buy one because of the short period of time I needed one they couldn't get these in time.
However the helpful chap (Jason) advised that instead of going onto ebay and using the 'Buy It Now' option for the Mongoose system (which was the next alternative) he simply said don't worry and he'll take my details over the phone at the same ebay price.
Top man indeed.
The bonus is that Amber Performance are 2 street away from me and as they are open until 6.30 pm each night I can collect the exhaust on the way home from work tomorrow or Wednesday.
Chuffed now.