Hahaha. Only joking. Two 8s would serve very well. It doesn't take much to add in low end. The single 8 in the back of my trailblazer getting ~150rms does a good job of making music felt, even at highway speeds. Sometimes I wish it had a little more, but then I remember I'm broke and it sounds good the way it is. Personally I prefer everything to be crisp and tight over booming and loud. And what I have now sounds dam clear and pretty loud. Even with the tweeters on the floor. Having every thing match, I learned early on, makes it sound a lot better then having more than enough power, but speakers that can't take it. It may not be as loud, but you won't hurt anything that way. It's all relative to the person listening that day, but generally speaking, a matched system sounds better to me then an over powered system. But I'd imagine the factory system in a mercedes is pretty dam matched so it's as simple as adding a sub to your liking. The only major issue I see is if it has like an adaptive eq and adjusts using cabin microphones. Then the sub may throw that off.
"it'll blow up" but yeah, my thoughts exactly. I can't see the systems liking the pulsing, uneven draw from an amp either.
Exhaust is too sweet!