I read an interesting note about the FR3 Handling Pack when it comes to wheel size, the FRPP catalogue mentions using wheels that are dimensionally similar to the factory wheel options but didn't elaborat eo nthe reasons why?

Off the cuff I can only think of upsprung weight and/or interference with larger wheels?

If its an unpsrung weight issue, that goes to show how sensetive a damper/spring set-up can be to weight changes in that area.