2 12's and 1kw????
And it's not enough???

Something is wrong with the install!!!

Fix that before you buy more stuff to make matters worse.

 

trust me you don't need a a third w6. I had 2 12" w6's in a ported box and i hit 144.9 off 1000watts rms(bd1000 willcam and citrate will account for this cause they helped me build it) and that was in a 92 cavalier so trust me when i tell you that 2 is good enough. Besides the box will not fit in the trunk if you were using 3 of them. As for the free air...i think that jl's hit way harder in a box than free air. You're gonna have to do alot of sealing to even get loud or hear a nice pound in ya ear mang. Don't go sealed unless its for sq. Mine was ported and considering they are strictly sq subs they still hit 144.9 off TL. Rich's mike(ntxxktd) did 145.8 this season and that's only on 1000rms.