you should not have to rejet for this set up. and i think u might have to use smaller pipe into the airbox. there is a write up on it in the how to section i think. u dont have to do it exactly the same, but it gives u an idea.I know this is the wrong forum but this is exactly my question! Will I need to rejet if I use 1.5" spa hose to the fender and then 2" for the riser? The bike is a 2000 foreman 450s, all stock. Thanks!