I have just ordered a 10" single bandpass system that I hope to be installing in the next week or so. I am also putting 6.5" components into the lids of the two boxes in the rear deck (first aid and tool kit). This allows the stock opening to be clear and I think I just have to pull the carpet-like material out form the bottom of the stock openings (grey) and this will give me two ports from the trunk without doing any cutting (except in the lid tops). I was thinking that the bandpass would push the sound out better and that it would move through the speaker openings easier and more clearly than a regular box. I tested this theory with a passive sub form my home bose system (acoustimass 10) which utilizes to 5.25" woofers in a bandpass enclosure and you could definitely tell that the bass was there. I did this with speaker in the stock opening and it sounded kind of muddy but I am sure this is caused by the sound going through the thick carpet-like material. I will take pictures of the sub install and the compent set install and post them here to help others out who want to put subs in a 126.

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89 300E Pearl Grey Metallic
7 Spoke 16" staggered wheels (SLK)
215/55/16 Hankook Ventus HRII H405 tires
Euro Headlights
Smoked Corners
Smoked red/clear tail lights

1987 300e Black Metallic (mom's car)
8 hole 15" wheels (C Class)
Clear Corners
Red/Smoked tail lights