A friend of mine had the BSW sub/amp and its truly amazing for the size.. That amd itmbeimg completely stealth are the reasons I went that route. I had considered the JL as that has been my go to for many many years. But you gotta love a company dedicated to your BMW. Soon i want to add the stage 1 upgrade speakers into all doors and tweeters... Im really waiting on the daynthey come out with the amp to match them, although I hear just the speakers alone are 1000 times better than stock..
Youd be surprised what a 8" woofer can do if the box is tuned properly like the BSW setup..
Personally im not interested in vibrating my BMW pieces and causing excess rattle when im not blasting my stereo. Nor am i wanting to stick a box in the trunk so thieves can break in and cause more damage to my car than the speaker was even worth..
My 2 cents.