im building my buddy a box for his 2 type r's, ported.. now alpine recommends no more than 2 cu ft per sub but that is gross volume... i didnt think gross volume mattered,, because once you factor in the sub and the vent volume your only getting like low 1's for your box,, and will that not hamper its ability to powerfully pick up those lower frequencies.. he likes the lows so were tuning it low 30's but this is also gonna make the port bigger which means even less net volume.. is this all because the sub still has to push the air inside the port as well ?? i need answers :\ ..
when they say gross they are talking about the space before the subwoofer and port. They are accounting for the known space taken up by both. Generally the larger the box to recommended max size the more youll hit the low end but usually at the expense of the upper bass and the sub is less controlled in the larger box.