He wouldn't, I just use prefabs as an example of ported performance. You can make them better, but the entire point is to get the resonance in the range you desire. In the case of a prefab it's usually 35hz because that allows cheap systems to sound deeper than their power ratings would imply, regardless of the quality. The failure of prefabs is mainly in the construction quality, there's a lot of losses, it's not sealed very well, there's no bracing, the box vibrates, it doesn't contour to a trunk because it's generic. Each of these things contributes to less volume overall compared to a well made ported box with the purpose in mind.
You can, but at what frequency are you choosing? You choose the frequency based on the shortcomings of the rest of your system, no? Point being that ported isn't the best box type to get the widest range of frequencies at a high quality. If you were to watch a sub in slow motion in two different enclosures, ported and sealed, the ported will return to center slower than the same model subwoofer will in a sealed enclosure. This means fast and deep music like hard style techno would be sloppier, whereas the sealed would give you the best chance of those beats sounding concise as intended by the song. The quality of a ported exists in lower tones predominately unless tuned to a higher tone specifically, but then you risk a lack of dampening on lower notes so you're once again stuck choosing a frequency to shine.
I've built ported enclosures. They do what they do best.
Yes, if you have a single vehicle (he does not) and the means and the know-how, you can peak in a productive range with ported chosen for the cab, but the other speakers are still the more important determinant factor in what range you want to aim within and ported is still limited to lower ranges unless you want to lose a lot of volume at lower frequencies in order to avoid bottoming out the driver (under dampened).
Not sure what you mean about the SPL sub, but a cheap poorly designed driver is bad in either, maybe you'd be correct to say it's worse in sealed enclosures because venting isn't as productive in a sealed environment and the coils will get hotter per watt. Higher frequencies also tend to be more noticeably bad when they are, hence why most multi-channel amplifiers aren't class D, so assuming your ported enclosure is tuned not to under dampen it's less obvious that you have a so-so sub.
Instrumentals don't produce the 35hz synth beats that rap music does, a kick drum is often the lowest note, which is anywhere from 50-100hz. Bass guitars by contrast are quite a bit higher in most songs, like 80-250. More noise than sealed, in which half the output is lost and the dampening also detracts from the excursion. Ported enclosures are louder than sealed at every frequency just by allowing air to move rather than simply compress.
Great as in broad range I suppose, if there's a subwoofer included in the car it's likely 8" or 10" and struggles with lower tones, but does a decent job at higher tones. If you can leave the mid-bass up to the Bose, you'll be able to add in a strong well-tuned ported subwoofer to fill in the only part of the music that you're missing. If however they didn't have a standard subwoofer included then they'd want an enclosure capable of mid-bass. If you're listening to instrumental music then 35hz is less important than mid-bass, particularly if there's a dip where the mid-bass belongs or there's an under-dampened sub trying to produce it.
Ain't no thing but a chicken wing.
