[Redromeo]

Subwoofer options for a 330i M-Sport convertible

I like the sound of my basic stereo system but the bass sucks for some songs.... I have a wide music taste but wold like to hear all my music in a way that dose it justice.

I would like to add a subwoofer but I worry about the space in the old convertible some people put one in the rear arm rest. What are my options I have read that people are adding the earthquakes under the seat but there are no reviews. Has anyone tried this?

I have the basic system but I have a single din media pioneer system with a focal solid 4 channel amp and a alpine m2000 mono amp in the wings but don't mind using the stock system.

I like the idea of the arm rest sub any other ideas.