ok you stated in your last post that you have differing peak frequencies for the 10's and 13. So just to put some numbers to help illustrate the point the 13 play up to 80hz and the 10s play up to 100hz. So up to 80hz they both are playing the same frequencies. this page is somehwhat helpful explaining
http://www.sfu.ca/sonic-studio/handbook/Cancellation.html
I would try and make one certain sub size be efficient at certain frequencies. The 13 be playing 53hz and down, the 10's playing the frequencies between 60hz and 125hz or so, those are just examples. i still would be interested in seeing this, from what i see you get 15 or 16v from the alty by what you say and don't see any extra batteries or what else, using sony or Jl amps on the subs, haven't seen anything to power the comps and nothing else in regards to your setup or something to crossover the subs to avoid cancellation and make it sound a whole lot better. but i might have to meet up and see this.