well would you look at thatI'd say get a death penalty 21" if you want a game changer.
Death Penalty-21 D1 Incriminator Audio 21" 1500W Dual 1-Ohm Death Penalty Series
Its not gonna be anywhere as close as the DP 21.If I go with the 15's I'm sure they will get loud just want to make sure the lows come with it.
These subs can work well in the space you have and will slam the lows better than the tnts for not much more. You dont have to tune to 20 hz, thats for home theatre purposes. 32hz tuning is perfectly fine in car audio applications.That 21 is ridiculous. Well by doin the 15's or 18 il save 200 and get me a g31agm duracell for the rear.