Done a few searches and have decided on the XS power ebay exhaust down pipes but they come with 200cpi cats whereas Zinram and Miltek have 100cpi. Is 100 cpi enough for a UK MoT and to keep the error code light off? I am going to look at welding a flexi in place so was thinking I might just buy the straight through pipes and 2 100cpi cats and weld it all together if 100cpi is enough. Conversly is it worth the effort for a car thats never going above stage 2? Keeping K03's so would 200cpi be fine for this and save the time and money of fitting 100cpi ones? Cost comparison is about £50 more plus 2 more welds to fit the 100cpi cats.