im just wandering what the major point in selecting a pipe for the exact year of the bike like a yosh pipe for a gixxer 750 2003 would not fit a 2004 ?? what the big diff ?? restriction ? would that affect that much the performance ??
I think the only difference is the bolt pattern, a 4-bolt vs. a 3 bolt. thats is the only difference, in the years of the pipes. Some pipes have less resctrictions, then others, like a race pipe for example would have less restriction than a reglar street pipe. Your really not going to notice that much of hp gain between the different pipes.
The only reason it wouldnt fit like was said was if itmounted different. All of the slip on pipes by different manufacturers will offer differing amounts of back pressure and sound deadining. So they will offer different sounds and a bit different HP characteristics. The peak HP #'s are over rated by most people. You also have to consider peak torgue numbers and where those peaks happen when choosing a pipe.