Help me for dB drag

[JLsystem 0]

Hi, i am looking for Street A class. My install is: Two amp EM-PHASER EA1800D, and two ALPINE SWR1042D. today i was build box 2.3f^3 (65l) and port at 45hz~ cross area 43.25in^2 (280cm^2) at 19.6in (50cm) long. so my result now is 147.4dB at 54hz. i have about 5kW at 0.5ohm linked amps (99.1V*51.7A). in Lithuanian street A class we can use one amp or two linked. so with open door result is 148.2. Somebody have an ideas how can I do more batter result?