On the meter or in your head and wow That had to be a shitty box my boy had an immortal it was an OKAY sub, Ten vs Ten my Type X (direct swap) sounded alot cleaner and were maybe a little bit quieter but thats with the Type X at 2 ohms and the immortal at like 1 i believe. Reguardless it died like 2 days later //content.invisioncic.com/y282845/emoticons/yumyum.gif.0556df42231b304b9c995aefd13928a8.gif Audiobahn or non-audiobahn still nothing special.actually the immortal is not made by audiobahn.. the sub gets very loud and can hold power.. its quad 2 ohm coils... very stout subs.. i had one 10 in immortal in a 2.5 cubic ft box tuned to 35 hz and it outhit my 2 06 model 15 in L5's which were in a sealed enclosure.. immortal had 2200 watts and the L5's had 1900