I have own two 18 mayhem in my day. They are amazing subs and can take a beating. I found both of mine off craigslist for exceptional prices.
My first one I ran off an ssl 5000 and it slammed but I knew it was not at it's full potential. It was in 8 cube box and tuned to the dirty lows. It was enough bass to literally kill my old car. I took it in after hearing an odd sound coming from the engine and they told me that something got lose and trickled it's way into the inner parts of the engine, in end having me to ire place the entire engine. That's when I said it's time for a new car. My conclusion is that mayhem caused that something to come lose. Literally murderous bass
I sold that one for a good profit
I turned around and bought another mayhem right after. That I fit into a new jeep lib in a 8.37 cube box tune pretty low icouldnt tell you the actual hz but it can slam. I ran that off tWo ap1500 monos And that really made it hit hard
That is also gone now though, traded to raptor for two w7 8s which are a more modest thump