Has anyone tried out the Blaupunkt flat sub woofers introduced in 2002 which come in 8 and 10 sizes, designed for vehicles. I never hear reference to them and they would seem a good way to go, unless they just don't perform well. But for guys like me who don't want to add the big boxes, or modify the ski bag area of the 528, this seems like a good sub woofer compromise. I'm an older fart who doesn't care if his car doesn't sound like a bass drum, driving down the street.