setting hpf and subsonic filters

ah my mistake, yes thats what i mean - low pass. If ported and vented mean the same thing then yes it is..

Do you say that as a good or a bad thing

Yes you are very right. On the low end i get this kind of flapping feeling/sound.. you are able to tell its low, but its not that loud.. but it still shakes my whole freakin car like none other. I have two 12" L5's.. as you know it's an SPL sub so i guess it makes sense to have it tuned higher than lets say if i had a W7.  The real reason theyre tuned so high is because i got 2 of them off a friend, and wanted to put both in. In a dodge neon that was going to be a trick, and i knew i was going to want them ported. So they had to be a compact ported which brought the tuning level up.

I am currently at a stock alternator and would like to save that investment for another time. What i want to ask you is.. could i take one sub out, make a bigger box, and have it be louder/ sound better? I made both the boxes im using now so i woudnt have a problem getting another one.

Yeah they are the same, i think different amps use different names depending on if its mono or a multi channel. It shows the similarity in the names if you use the right words.. "let the HIGH frequencis PASS" and "block SUBSONIC frequencies"

That would be a slightly odd, yet correct way of desribing it.

set at 35 cycles, you would only get freq. ABOVE 35hrz. So yes,  high pass.