well they have alot of exhuast area which can be good but sometimes bigger isnt always better becuase you will lose a good deal of velocity this way.i have no doubt if setup right they will run better than a stocker likely could . a 2 stroke is bascily like a pump ,you want to get it in and out as fast as possible for best efficiancy .another concern is the placement of the sub exhuast ports,the whole idea is to gain chordial width, area, and still have ring support and the lasleeve sonic does this in a better design in my opinion