how important are these plates? as i apear to have forgoten them, chassis is fully painted now aswell

If they are to add extra stregnth to the join between br1/br8 and br2/br9 do you think id get away with leaving them out seeing as ive added extra large 6mm plates for the engine mounts to sit on? I cant even find any mention of them in the book apart from in the appendix.
