I would get an FBMFSW from a TT & A3, that will be fine, dont touch A6/Q7, think they're slightly larger, A4 also will fit but you want matching airbag & I see A3 & TT with airbags included mostly, also the airbag loom on A3/TT are already 100% compatible & wired correctly where as A4 might be wrong & require adjusting with pin moves to make work fully, just to save you hassle go for A3/TT IMHO