recommended sub-woofers for tekton double impacts?

Check out the Tekton thread by Corelli; you will find many specific sub combos and owner evaluations.
Also, be aware that a number of us DI owners find there is no need at all for subs. Suggest you check the response out with your room when they arrive and check the frequency response with a program such as REW (available free on the Internet). My room is fairly large (roughly 23 X 25 plus multiple openings) and the bass has to be slightly reduced to get a more even frequency response. Am getting plenty of energy down to 20hz.

Rythmik. HSU is great too, but it doesn’t have as many room/system integration options (such as only a polarity switch instead of a knob).

Reach out to @sbayne

@chrono318  I paired my DI's with a pair of sealed Hsu's--see my systems page.
I'm very happy with the result.  Gives me that solid foundation to just below 20hz that I was after.  The controls are quite helpful with system integration and I find that Hsu was a very nice company to deal with.  the value is very high on this product--just like the DI's.  I bet the Rythmics are great as well. Their gloss finish would complement DI's with an upgraded automotive finish.

I’m using JL Fathom F113. Awesome sub! When I turn it off I honestly don’t notice too much difference for music but it does integrate well. I run the DIs full range and crossover the sub at 45hz.