After 1994 all the 400's had 53hp restriction. Are they actually limited in some way or just designed to put out that much now anyway? The CB-1 and pre '94 Super fours puts out i think about 58-59hp. So is it possible to reclaim this extra bit or are the engines completely redesigned to just put out 53 now. I mean what are the differences of the pre 94 and post 94 Super four engines. A 5hp increase would certainly make a difference.

Don't know. I imagine that if the post 94 models have lower BHP then there would have been a bit of a change tuning wise, probably in the carbs. I'm sure with a lot of work that it could be done but its whether it is worth it for that extra 5 BHP (a couple of extra BHP can be achieved with an exhaust mod can't it and probably for cheaper?)