Thanks for the input guys.
With regards to it not making it any faster - that's fine, I'm not after that, I'm after a pretty tip and a better sound.
As for a weld and remap... I've tossed up the remap several times and I always end up at the same place. I could spend £500 on a remap and the car will feel a chunk faster for a while. Then I'll get used to it, and it will feel normal again. And I'm really back at the same point, just with a car that's putting more stress on the drivetrain.
99 times out of 100 the standard 230hp is enough anyway, adding more power just makes it faster in a straight line but it's still the same car, it's no more special, doesn't handle better etc etc.
The exhaust upgrade is just because the old one is on its way out. The sound and aesthetics can be enjoyed a lot more of the time than 50 extra hp can, in my opinion.
Re: custom exhaust, don't good points about unknown quality and end product.. something to think about.