Hi,
   I have a 2021 a force 450L and was wondering where abouts the ECU is as I have put a rear box on and am thinking its under the rear box! So will I have to remove the box when I get it upgraded? Thanks 😎

On my 2020 the ECU is under the seat, on the left side of the machine right next to the battery.  I can take a picture if you need so just let me know.