I have a buddy with a pair of these 15s wanting me to do a wall for music in his 2000 ford taurus..He had a guy from New York that did the recones for him and added a nylon .25" spacer between the basket and motor..Wanted to see if anyone had some experience with these subs I have never messed with them and trying to find out what kind of airspace they needed..He is running 1 OKUR 7.5 to the pair..On DCs site for the M2 version they say 3.75 per for airspace..Thanks for any help..