low bass

I want to know if anyone has spl numbers for lower built/musical systems. I can find people's competion numbers but I want to know what people are hitting at 25 - 35 hz, not 50 hz I guess I want to know if my system is in the right place for the equipment I have or if i need to build a new box...

ok so i have a FI Q 18" (fully loaded) off a cadence dakota 1200x1 rms amp. on certain songs and after played for a while, the sub will bottom out on certain songs. (i was told that weird noise was bottoming out) ive searched n searched but all the ones i found were discussing ports...i have a...