I have 2 of these on a ZX2500.1 in a 9 cf box tuned @ 31hz. Does 143-146 metered on music. Flexes your car easy, 3 inch roof flex, door & window flex. It snapped my rear view mirror off after 3 weeks. Sadly, one of the woofers blew today. While I was listening to music, they just started popping and smoke started coming out of the port.. I wasn't clipping the amp, my gains were set right, and bass boost was just a tad over half. But these subs POUND but seems like their durability isn't the best around.