Hi. I just made and account to make this post. I have a w211 mercedes sedan with non-folding rear seats so the cabin is pretty well sealed from the trunk. The vehicle has harmon kardon logic 7 system from factory but it is basically garbage. I added a 5 channel pioneer amp as well as a JL 12W0V3 Subwoofer in a ported box in my trunk. I ran the stock harmon kardons in the cabin through the pioneer amp and ran the highpass filter higher than factory through them and got much better sound out of them. Sub wise the I was running the 300w JL on 350w RMS and I blew it after a few months(Im stupid I know..). After running the JL on 350rms it sounded great when I opened my trunk and stood outside it but inside the cabin since the trunk is so well sealed from the car I barely got anywhere near the bass I wanted. I also want to mention my amp can run 350w at 4ohm and 600w at 2 ohm. My new plan was to just get a 12 inch pioneer champion sub rated at 500wrms and run it in the ported box in the trunk again at 500w rms on my gain lowered with a voltmeter. After thinking about my issue with the bass barely making it into the cabin I thought maybe a subwoofer in my rear deck would maybe be better at providing bass in the cabin. After doing some research on infinite baffle subwoofers I found the AE IBU12 interesting but its very expensive at 500$. I also read on some forums that using regular subwoofer in this application may require me to run the subwoofer at half its rated power to ensure I dont bottom out the sub. I am also aware a Qts close to 0.7 is good and a low Fs is good and a high Xmax is good. The pioneer champion subwoofer has a Qts of 0.73, Fs of 38, and Xmax of 11.3mm. I am now in a dilemma of if I should run the subwoofer in my trunk with a ported box at 500w at 2ohm or run it on my rear shelf as infinite baffle at 2/3ish the power rating at 300ishw rms at 4 ohm (since my amp can do 350 at 4 or 600 at 2) Im not sure which method to go with. I just want good quality bass inside my cabin and am not sure what method to go with. Also the subwoofer comes in 4ohm SVC and DVC so if I do the 300 at 4ohm I would buy the SVC and if I did 500 at 2ohm I would buy the DVC. If anyone has any advice with a similar vehicle like this or any tips regarding any of this I am open to everything. My budget for my subwoofer is <200 usd. And I can fit upto a 12 inch in my rear deck. The amplifier I am running is the Pioneer GM9705. Thank you