Just an up date, I checked today and my exhaust was direct from Play Mini, they were very helpfull, all they need to know is what shape bracket you may have around the back box due to a design change at somepoint by BMW Mini. (KINGDOGGY this is where you might have gone wrong) Also this exhaust includesthe centre long pipe too.
The back box will eventually go and start blowing out somewhere. If you are interested in the Play Mini you can hear it on You Tube, YES thats right some people are sad enough to video the sound of their exhaust

worth a laugh anyway so check it out!