Ok matta.
You seem to want a sporty note without sounding like a drag racer.
This was what I was looking for, and you'll need a new exhaust for this. As the backbox will still need to be silenced to avoid the loud everything. A standard cat back system will range from £250 - £300 depending where you go.
Mine has been on for a few days so has not got to it's prime yet, but it idles and drives perfectly normally, you wouldn't tell the difference to be honest, but when you're jumping out the hole, or are on it on the motorway, you can just hear that lovely rumble. It's fantastic.
Just ask yourself a few questions first, if it's power you're looking for, where will you stop (I'm getting worried how much I want to spend on this car), and do you really need it. Personally, the odd £300 is far from pocket busting, but obviously to each his own.
Good luck with the search, I wouldn't go off sound clips from the net, I have a video clip of mine (if you want it then send me a pm), and for the most part, it's just one noise, and that's the lowest frequency my camera will record (because the system has such a deep sound), but in the flesh it's gorgeous.