I have the BMC CDA on my anni

get a deeper note and you can hear the wastegate a lot more (I don't have a dump valve).It looks the nuts under the bonnet too as it has a carbon fibre effect. I paid I think about £185 although don't quote me on that (plus the £87 for my insurance - I was 19 at the time)
Here's a pic (be warned it will prob be massive and when this pic was taken I had no filter on the small tube hanging around in mid air next to the engine cover!!!):

Hope this elps you make your decision!!
Jon