Has anyone ever seen smone build a badpass box and port it through the first aid kit in a 300e. This is what I'm thinking of doing but I dont want to go cutting holes in my rear deck unless it is going to sound good.

I did that in my 300E. It made a huge difference in the level of sound compared to before I cut the holes. But many people on this board have recommended that you try taking out the rear speakers before cutting holes in your car. I've heard this makes a great improvement in the amount of bass entering the cabin(but not too great for the rear passengers).
I took out that bandpass and now have two 12's in a sealed box. In my opinion the new setup hits much harder and just sounds better in general.

Mladen

Bandpass boxes, in my opinion, sound terrible - they get good numbers, but really don't sound very good. All you get is really high spl at one very small group of frequencies; they sound pretty bad and are very hard to tune properly. I would recommend a custom ported box - have the sub firing towards the taillights, and the port on the top of the box firing through the rear speaker holes. You can either have a port outside the box directly into the cabin, or just a normal port under the hole. Email me if you have any questions about external ports. Good lucK!