Found this site with all race/rally spec exhausts on for peanuts compared to what you pay over here, get google translate. They're priced at 499 euros each which off the top of my head is about 370 quid, the group N and others are on there. Not sure about shipping costs but for those of you that are taking altering your clio more seriously lol could be for you
http://www.mtk-tuning.com/zoom.php?ref=4132
http://www.mtk-tuning.com/zoom.php?ref=4132