Do you have one or two subs? A single 4 ohm driver can't be wired down to 2 ohms unless it has dual 4 ohm voice coils. 29Hz is a pretty good and low tuning so if the volume of the enclosure is also on track, I'm going to venture a guess that "sla-4 bass hi" is the problem. The boost associated with it is likely to be in the upper region and with all of your other settings being pretty much flat, the low end may be relatively lacking for that reason.
Try this. Turn the sla-4 bass off and leave it alone for a while. Instead, don't be afraid to extract the frequencies you like by using the appropriate low pass crossover frequency combined with some responsible EQ. A flat EQ doesn't sound good. EQ is meant to compensate for uneven frequency response and can also add that warm, smooth sound with a little twinkle on the high end to make listening more enjoyable on a daily basis. Loudness settings are okay for the same reason, they work well when used properly.
Try setting your lo pass to 50Hz @ 18 or 24dB, just to start with. Next, use some DJ Billy E, DJ Droppin' or something similar with constant state bass tones that go from high to low and try adjusting your subwoofer level relative to the midbass up front. Then adjust your EQ by bumping the 30Hz area by 2dB to 4 dB, or more preferably by lowering the 50Hz or 80Hz bands by that amount (but this can also impact your front midbass), see if this is going to give the balance of frequencies you are looking for. Don't adjust these 20Hz & 30Hz bands too aggressively because it will require enormous amounts of extra power (leading you into clipping land) and you can also run into over-excursion issues. As necessary, you can readjust your subwoofer level for the best match to your frontstage and If you want more transient attack or slam for the midbass you can raise the low pass setting to 63 or 80Hz. You may need to adjust the sub level back down after raising the low pass.
This is just one approach, many will work. But this will get you started in that direction and if you still can't seem to get what you're after, you may need a line driver or there may be something off in your wiring or something else that was overlooked.