it is a tossup...i dont like mtx subs...but i will put that assid i have hever heard a thunder 8000 on enough power..but i heard a pair of he2s on a fosgate 700s and it was pretty loud..good comparison...
ummm...pretty sure the 8000's will win hands down, i have some 6000's and i think they might be comparable to the HE's, of course they would have to be powered sufficient