Question about 20's on Mazda

How much trouble is it to tub the pass side firewall to clear laying on 20's. I know the heater box is back their just curious how much fun I'm going to have this weekend!!! Cause I want to keep my heat and A/C, Old Fat Man don't like to get hot or cold!!! Thanks in advance for any input.

If you stock floor you're Heater box above tranny is not an issue , but you're A/C box is very very close to the tires when laying 20s . You can either modify the box or move the cowl underside upwards 1 inch .

Just stock laying frame on 20's, no body drop or stock floor.