Hello there. Few days ago I just replaced the two front speakers on my B&o system on A5. The difference is huge as I never knew there was a problem with it until I changed something at the door panel and saw they were broken. Anyway, with all the "new" sound coming to the car, I was wondering if I can do something to upgrade the bass speaker on the trunk without ruining or de calibrating the system. Anyone did it? Also, is the trunk speaker the only one responsible with the bass in the car?