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Do you want bass or quality? Generally, sealed boxes are better for quality, with ported boxes being better for bass. I haven't fiddled with a bandpass box so I can't tell you anything about it.
A reputable shop should be able to do it. But im willing to bet they will try and talk you out of it. The box needs to be built to the in cabin resonating frequncy of your car.
All cars have a resonance frequency its what freq is the loudest in the cabin. if you powered a speaker with 100 watts and played a bunch of differnt freq notes the resonance frequency of your car will be the loudest note played. you can determine wich is the loudest with a mic used to test SPL such as a termlab or audio control.