I did it to my 260E with 1 10" Soundstream Sub (infinite baffle) and use the stock locations as ports. It's installed from inside, through the trunk, and will put use a linen type screen that'll cover the whole rear so it doesn't show. It's still not hooked up though, but it sounded great in my brother's car who had it in his car, which was not as air-tight as this car. I will be running it at x-over point 160Hz and below.

I'm not sure how 2 12"s would sound, but might not be as tight as 10"s... just my opinion... Hopefully your subs are designed to run in an infinite baffle configuration.

good luck...

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sjsfiji

'87 W124 260E (DD)
98K orig. mi. @7/15
CLK 7-Spoke Forged Wheels
Neuspeed springs/Bilstein Sport
4/3 bump (F/R)

'97 993 Carrera
106K orig. mi.
Always driven like it's stolen