The downpipe cat is the big one that does the most work. Yours is a Prodrive bug isn't it? If it had the PPP fitted, the second mid-pipe cat should have already been removed (but the original heatshields remained so it still looks like the cat is there!). Worth getting under the car and checking.
The bulge in the long straight centre pipe (about a metre long) is just a noise resonated section and does nothing for emissions.
You should be able to pass an MOT with only as sports-cat in the downpipe, but the car should be remapped to cope with the change from the standard downpipe.
