sigs are mean, from what I remember of the good ole shocker days (like 2000-03ish) the shocker 18"s like about 6.5cubes + 8 would be better and the spl guys were running like sd port area.. and for spl the modo was as much power as you can afford LOL. dunno, maybe 2-3k daily and more fur burps depending on the soft parts build. from what I remember sigs could use MT parts. and were louder than stock of either... David/PSI could probably do some awesome recones for these and more than likely has the specs down to just build you recone kits without even needing the motors...
they're loud that's for sure... I used to run shocker back in like 01... Mike Ankely or something used to run it. think he's still around sometimes on termpro..