Ok, here is what I came up with on winisd. I am pretty much set on going with the micro cube, but am wanting to make sure and use the best possible driver so I can get the most out of the size of the enclosure. In the graphs the Yellow is the micro with the SI D4 15" and the Green is the Dayton 390HO 15".

The settings I have it at right now are for 1 driver in a 3.75 cu ft. (106 liter) enclosure both tuned to 21hz. The SI is getting 1100W, and the Dayton is getting 650 (will be using the Inuke 3000dsp and have 2 subs in the end). The SI has a second order high pass set @ 18hz, and the Dayton has a 2nd order high pass set @ 20hz (in order to control cone excursion). The spl reading is at 1m since these subs will be placed nearfield next to my couch as end tables.

So, here is what I am taking from the graphs

Transfer Function Graph:

-3db: Dayton = 29.3hz, SI = 26.35hz

-6db: Dayton = 22.5hz, SI = 22.3hz

-10db: Dayton = 19.0hz, SI = 19.1hz

Cone Excursion:

Dayton (12.5mm xmax): maxes out at 13mm @ 14hz

SI (22mm xmax): maxes out at 22.5mm @ 12hz

SPL: (difference between SI and Dayton at each frequency with respect to the SI driver)

100hz: -2.7db

80hz: -2.9db

60hz: -3.3db

50hz: -3.5db

40hz: -3.8db

30hz: -3.7db

20hz: -2.1db

16hz: -3.0db

Does anyone see anything wrong with how I set all of this up? I'm fairly new to winisd so I want to make sure I'm not totally messing things up and coming to the wrong conclusions. If I did set everything up correct then it would appear that the SI driver will provide an average of 3.1db more output from 100hz to 16hz than the Dayton at a lower price (~$145 vs. $173).