It has been my understanding that with the F-20, you will get gobs of output from like 50hz and up, but it doesn't extend very low, probably 20hz or so with some lower dbs at that point. I would go with the duel sealed SI 18's. You might not get as much output but they will extend lower. I am not sure about that lilwrecker or what ever it's called, and I may be wrong about all of this, so I am interested in hearing some other opinions on this. I would imagine that if you did go with the F-20 variant, using a high quality Stereo Integrity 15" driver would be better than the Dayton DVC15, right?