T/S parameters are the measurements of a woofer that define what type and size of enclosure to use. This sub's parameters indicate an EBP of 44, which defines it as a sealed. You can change the box type to vented, but be aware that there will be trade-offs involved. The big trade-off you will find here is that you will need to build a much larger enclosure than you have now.
Ideally, your subs should reside in a sealed box twice the size of what you are using now. That change in airspace would drop the peakiness down by a decibel and lower the F3 by about 5 Hz. F3 is -3db down from flat response and is considered the low end limit because at that point it is receiving only half power.
To change to a vented box: give up enough room in the car to build a box that will have 5 cubic feet of airspace dedicated to the subs (2.5 to each). The box tuning has to be very, very low to achieve a good response, which means that there will be little if any sound produced by the port. Because of this, the port itself should not have to be built as a slotted-type with all the extra displacement associated with such a type of port. Instead, use a round PVC tube.
Here is a look at responses for this sub in WinISD. I had already had this driver loaded in the database so it was a simple matter of just opening it up and trying a few different things with it. Open the file, expand it to full size, and refer to the colored response lines that I will describe to you:
swe1242.jpg
Yellow: this is what you have now. 2 cu ft sealed, F3 is at 43 Hz (follow the line as it crosses the -3 db purple line).
Orange: this is what I would recommend you change the box to. It is also sealed but the box airspace is almost twice as large at 3.75 cubic feet. You see that the peak doesn't go as high and that the F3 is pushed a little lower to about 38 Hz. Would work well with any type of music and is a better SQ curve.
Teal: this is what you could do by venting a box for these subs. 5 cu ft of airspace after deducting all displacements (such as port and drivers, and the added braces you will have to use). The response goes up a little peakier than the orange curve but not as bad as what you currently have. The F3 goes lower than either of the sealed types, to 30 Hz, which corresponds to the Fs of the driver. The port is a PVC tube that has a 4" interior diameter and is cut to 14" in length. This makes the box tuning at 20 Hz.
Now, because the tuning is so low, there will be very little sound emanating from the port structure. You don't need to build the larger slotted port design (with its inherent larger displacement costs) because port noise will generally not be an issue at this low frequency. And, tuning to a higher Fb by using a shorter port would result in a bad response curve....it would cause an abnormal peakiness to the sound. Also, changing the box size to anything less than 5 cubic feet would give you an abnormally bad response.
Bottom line: I suggest you rebuild your box as I defined above to the larger 3.75 cu ft sealed. If you want to experiment with vented, and have the necessary space to do so, use what I showed here and nothing smaller.
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
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