Eh..you will notice a difference. With rotary carb at idle and for the bottom part of the power band, the air flow is bent due to the carb arm's position. When it's at mid or high speed, it's straight. They are great for ST's in mid range where they need it to get over those jumps. Slide carb is better in low and top range. THIS DOESN'T MEAN YOU HAVE TO GET ROTARY FOR AN ST AND SLIDE FOR ONROAD. Some people who run CVRs use the slide carb one as they want all the power they can get. Rotary carbs are easier to tune, but if tuned properly slide carbs will prove to be better.