We posted this up on another forum and the response has been pretty good. They seem a popular option here, although most say they are expensive, we get a very good discount which makes them certainly affordable!
http://www.magnaflow.com/02products.asp
I know they're pretty solid in the US, especially for custom fabrications, but I am wondering what the demand is like here, especially with the likes of RPS and co being readily available. If you want a quote on a part just link me to it!