Quality of the product, service and response/communication from Seller are excellent. Only problem is sometime the Subwoofer are not exactly Plug & Play as size and compartment varied between car and model. Ordered for E71 X6, housing need some DIY to make it fit and when fitting/assembling the subwoofer to the car, the height of the subwoofer are much larger than the original sub, thus, the plastic grill covering the sub can't be screwed back. Other than that issue, Seller are always prepared to help out and assist in any of our queries and issues faced.