did you read the post above you? your idea of the sealed vs port is all wrong. depends on what you want out of it. my 18 is tuned in the lower to mid 30's and i still have my tight bass as you called it. i can throw on some metal and all is good. may not have the output of a higher tuned box but it plays very well on heavier music. the difference is the sealed box there is no tuning as the ported box you would tune your port. build a ported box for just one so you dont waste a lot of wood and see how it performs. you will be much happier with all 4 ported than 2 sealed and 2 ported.