Claire,
One thing I would say though, is don't get another Renault one...they all fail...its not a case of it, but rather when!
I wouldn't recommend K-Tec, as I've never seen, heard or had one in the flesh. I only recommend Pro-Speed as its what I have got, and I wouldn't want someone to waste their money on my recommendation. Its piddling down outside, but I can try and take a pic of how it looks later, you can see the back box and tailpipe, but it is hidden behind the bumper. Also, you'll lose your 4K rattle...and it will make the car sound a little more 'meaty'.