2 12w7's with P.A. tt2250d

I was running 2 15" cvr's in a sealed 5cft box on my tt2250d and it was pretty loud but I kept having problems with my subs.So I bought 2 12w7's put them in a sealed 4 cft box, and it souds pretty damn good for some 12's but I was hoping for louder. I hits low like the 15's but with a lot better sound quality. If I were to build a ported enclosure should these 12's be able to hang with the 15's?

I'm using the same amp, but when I was running the 15's it was on a 1 ohm load. Now with the 12's it's on a 1.5 ohm load (less Power).

I'm in a 91 dodge shadow (4 door hatch back)

Any input would be greatly appreciated.