Too little pressure, but why???

Hi, I have a problem. And that’s the feeling that my Woofer somehow doesn’t bring the pressure he should. It’s an SPL Dynamics Pro 12D2 on an Emphaser EA2350. He gets laso 1.2KW as that belongs to a SPL Dynamics. He sits inversely in a 60L net box with four 47mmx280mm pipes. My car is a 73 Plymouth satellite, ergo a large, heavy Ami. The current is not yet perfect, as the lighting engine performance is too low, but otherwise the OK should be. I think maybe it’s on the floor.