My old rf pro series was a beast, thinking about the box i had it in 

  thing was fing huge. 
I dont remember the exact details, but the box was around 9 cubic ft. 6 ft for the rear chamber with 3 4in ports around 10? in long. The front was 3ft with 2 6in ports around 3? in long.
I remember i had it tuned LOW.
Made a few people puke from the bass at partys when i set it up corner loaded in my house 

   ...and a few girls really liked sitting on it.
lived most of its life in a 85 rabbit gti, with no back seat left. It wasnt pritty  

  but it sounded great running off of my ms2125 (i wanted a bigger amp but that was all i could afford back then)  used to roll down the windows and that thing would come alive 
 
 
Had it in my buddys suburban for a while to, but one 18 wasnt enuff for our spl cravings in that big thing...
I had a 8 ohm pro 12in i picked up at a pawn shop in everett wa. that dissapeared with the 18  

   had it in a custom 6th order box for a 85 cellica gts  ...never even got to test it in the car because i was waiting on my 1 in plexi cover for the box when it grew legs
...ah well, gave me an excuse to buy the titanium 12s i ran for a few years 
 
I also always liked the original kicker solobaric 12s    things sounded great in little sealed boxes with a ton of power, i dont remember hearing anything that could touch them when they came out (in a tiny box)