Just FYI, i got one of these recently and whilst i believe that they are an option on all supra's there may be a problem re the undertray.
Far (anyone) do you know if the front undertray section will be retained with the new bumper (i'm thinking no!)
Ben does your currently spoiler less car have x2 slots in the undertray an inch or two inside the two slots where the towing points come down? If not you will need Far's type of undertray or leave off your one. I mention this as i was looking to fit one myself but my undertray has no slots for the active spoiler mechanism.
Given this, the following is a bit of a long shot! but if Ben has the slots in his undertray and you (Far) have no use for yours once the new bumper is fitted, could i have it so i can have another go at fitting it?