HI THERE, I READ SOMEWHERE THAT SHORTEN A PIPE GIVE BETTER LOW END (TAKE-OFF) AND LENGTHEN A PIPE FOR TOP END, AND THIS WAS ON 2-STROKES. i GUESS THIS MIGHT MEAN YOU MIGHT NOT HAVE BOTH, BUT I`M SURE SOME OF THE GUYS WILL HELP YOU WITH A HAPPY MEDIUM. LATER....DOUG D. IN VA.