Am I right in say that a higher frequency box will have more output? Like a 40hz box will be louder than a 32hz one?
What differences does it make in SQ, how much louder will it be? How well will it handle low notes?
To an extent, yes higher = louder. This is because your vehicle has a resonant frequency. When music (or a burp/tone) is played at or near that freq, the vehicle vibrates and increases perceived output (as well as on a mic). This phenomenon is called transfer function. Most vehicle's resonant freq is towards the upper end of the subbass region (45-80hz), so tuning closer to this freq will help the box tuning, and vehicle tuning, work together. Now of course, if you too too high, you would go above vehicle tuning, and output would diminish. But thta would be radically high tuning, out of subbass range anyway.
Vented enclosures will allow your speaker to 'unload' below the enclosure's tuning point. To put it in basic terms, below the enclosure's tuning point it loses its 'air spring' on the cone very rapidly. A song that deviates very far below the enclosure's tuning point may allow the speaker to bottom out and be damaged.
Generally for the lower tuned boxes (28-34hz) no concern is necessary. No music is likely to deviate far enough below that tuning to hurt the speaker (unless you burp low freq tones). 40hz is getting about to the point Id start wanting a subsonic filter to block out too low of bass. Usually set to one octave below tuning... 20hz.
The higher you tune, the output you get, at the expense of low-end reproduction. Again, the enclosure unloads rapidly below tuning, hence ithe system doesn't like playing notes much below its tuning point. Drastically high tuned boxes (60hz+) that are designed strictly for SPL, will experience somehting called being a 'one note wonder'. Basically all the bass coming from the system sounds the same. Very little definition to the sound.
People wanting strictly SPL will tune high, basing it on the tuning freq of their specific vehicle (usually 45hz+). The SQ/SQL guys will tune relatively low in an attempt to gain as flat a freq response as possible (28-34hz). If you fall somewhere between those two distinctions, you'd chose a tuning somewhere between those two windows.
This is of course, speaker VERY generally. Some subs do not even like being tuned below 40hz, some perform different at different tuning freqs, etc. Do not take this info as speaking for every sub in every situation. Hope it helps.