This rear floor to shock tower brace closely follows how BMW Motorsport reinforced the factory E46 GTR and touring car shells into the rear floor/subframe location.    This brace performs several functions: Rear floor reinforcement to combat stress fractures at subframe mount locations Rear shock tower reinforcement to allow coil-over-shock (aka true coilover) installations. Lateral reinforcement and structural replacement after notching the factory floor crossbeam for Quick-change differentials. Longitudinal torque load distribution for less overall floor flex under hard acceleration (basically it stops the rearward subframe points from pulling down as the differential applies torque through the subframe) Includes hardware to bolt into the rear floor/subframe threaded tubes, or you can use your own M12 all-thread to allow through-bolting with subframe below, plus nuts in cross bar feet.