change box type

You're not giving up much info if you want some help.  But I'll make an assumption here:  you say "subs" so I'm guessing you have two of these Type Rs in a 1.25 box.  If that's the case, sell your present box to a buddy.  These subs come as DVC 4 or 2 ohm, and I'll assume you have two of the SWR1241D models. 

Build a new box, that when complete, will have a net airspace of 4 cu ft.  Included in that box size will be one slotted port built with the dimensions of 10" X 2" X 11 1/4" long.  And some reasonable bracing in the middle of the box...which means that your total box interior volume has to be large enough to account for these (and the two drivers') displacements and end up with 4 cu ft of air dedicated to the woofers.

If you don't have the ability to build this yourself, find someone to hire who is able to build it for you.  Your subs will perform much better than what you are presently experiencing.  Click on the following image and expand it to see what the sound would look like when modeled, but the actual in-car use might be a bit peakier in the middle freqs.  And read my WinISD guide stickied above for more info and how to understand this chart:

alpineswr1241d.jpg

Oh, and by the way, 1.25 or 2.00 or even 3.00 cu ft ported for two of these subs would be much too small with badly peaked responses, overly long port lengths and severe loss in the low frequencies.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

rrcustom, what are you basing that on?

1.25 cu ft is good for ONE of those subs sealed.  For two, a good sealed box would net 2.5 cu ft.  That's why I said to sell the box you have if you've got two subs in it.  Here's a comparison showing the ported (as I linked in the prior post) along with a 2.5 cu ft sealed box:

swr1241dsealed.jpg

Just about the entire sub musical range follows a straight line in the vented response.  It doesn't matter that it's 1.5 db above the flat 0 line in this case - that line is where the majority of music sub tones are taking place.  The response doesn't start freefalling until it gets below 40 Hz, and F3 in this chart (for the ported response) would be considered 3 db down from the +1.5 db line, which would be -1.5 db.   When you look at it, you see it hits 30 Hz at that point.  That's ideal for this sub.  I would use a different sub altogether if using a sealed box.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

sorry about the info...im useing a dual sealed box and each sub is sealed off and the cubic space is 1.25 for each sub....i am running 2   (2ohm + 2ohm dual voice coil swr222d) but i have each amp bridged to each sub at 4ohms....so are you saying make a slam box like the one that mtx's sells? and would it be easier to fiberglass a ported box or make one from MDF

stevdart what is that program called and where can i get that from?

Did you mean to say 1222?  The info above will be wrong for your subs, then.  I can't find the T/S parameters for the 2005 products online.  The parameters will be different and so the box size, port size and tuning freq will be different.  If you have the owner's manual, you could carefully reprint those parameters and I'll have a look at it.  I'll also want to know if the manual indicates that the parameters were measured with the coils wired in series, or if they say anything whatsoever about how the measurements were taken.

Neither type of box-building is easy.  But you have to know how to properly construct a box out of MDF (and actually do it) before you get into fiberglassing.  That's advanced 401 course stuff  ;)