You need a map that will put the MIL light out and let your engine know you have a decat, other wise it overfuels, and actually loses power,

the guys over here will help you out mate http://bbs.rsownersclub.co.uk/forumdisplay.php?f=134

also the tech section has a full list of error codes and their meanings, its a very busy forum and plenty of people who can help you out.