So in the title you want to play louder than lower, yet two references in your post state you still want to be able to play low. As far as comparing the SA-12's to the T3 audio 12's, did you just simply, switch the subs out in the same box? If so that is probably the reason why. Different subs like different enclosures. ANd to be honest, that is key to getting what you want. A properly designed box will give you the results you want.