Custom subwoofers for your BMW? The X5 (E53) BMW car is great but lacks a decent bass response in its sound system. Cartronics fit custom subwoofers for BMW in sealed box to give that bass response, with a mono amp & modify any RCA outputs.
See an example installation here
We can supply the JL Audio Stealthbox on our online shop.
Or call us at our Surrey workshop on 01932 800800 for more installation details