OK, I am finally going to upgrade my stock exhaust to a single can. Favourite at the moment is an Exan exhaust. Is changing from the stock a simple "plug and play" matter, or are fuelling mods necessary? (My Ten is pretty stock as far as engine and fuelling mods are concerned). My main reason for changing is to save weight and my biggest concen is reducing the fuel efficiency. Anybody able to put my mind at rest? Does a single pipe mean less MPG (or better?). Anything else I should know about single versus stock exhaust? Pretend your explaining it to an idiot, in fact, no need to pretend. Cheers all.