Kicker L7 is sq, wah mahraj wah
Farrukh u need to understand one thing. If ur goal is a few mins of boom to impress the boys n girls :P, Go with The spl option else if u like daily listening at pleasant volumes sq subs then.
i like a sub that goes very low, even at low volumes without shaking everything and creating an imbalance with vocals. Jbl range is gud for sq locally.
Also cosider the fact, there is not much use of tunings like 30hz or 28hz, because the are mostly restrictd within ur car, will flex it badly but dont sound very prominent just tons of air displaced.
i say get get 2 soundstream splx, get a box by sir kevin at 38hz and boom boom farrukh