Yes, try a 15-18" sub.....or more subs.
Yes but makes sure it is low Q. Since most manufacturers do not publish this then simply go large sub sealed box - since ports resonate you should advoid them as it will add volume without the transient dynamic pressure you seek. (think of a port as smearing energy over time - it takes the back wave and adds it to the front wave of the next cycle)
Thanks alot everyone! My room is 11x17 with the standard 8 foot ceilings. Have recently purchased a used rel q108 and really caught on how to dial this little wonder of a sub into the system, only I'am left with an itch for just a little more "pressure". This is the best I know how to describe it. Not much on measurements, just like to trust the ears. Was considering trying to find another one, as suggested, yet I'am unsure if it is possible to connect two of the neutrik speakon to the one amp. Have a YBA integre which the sub is connected to via the speaker posts. Anyone with experience? My curiosity is if this is not possible, what kind of change would come along if the 8" (q108) was replaced with a 10"(strata 3). Both are sealed closure. Having fun now........