I'm going to be the protagonist here and say that I had it done, i liked it to start with but I quickly got quite tiresome of the flatspot and the noise is not exactly refined. Very tinny and raspy, sounds like an M3 but without and of the low tones.
In the end I just bought a full k-tec system, sounds MUCH better, I got alot more remarks about how my car sounds now.
Obviously it's only me saying you shouldn't, it's a cheap mod no doubt, but if you can spend 15-20 grand on a car, £400 for a decent exhaust shouldnt break the bank....