What usually gives u the best results. 1 15. Or 2 12sThat configuration works very well with the subs offset to the passenger side facing forward and the port firing into driver side rear corner, but 2 fifteens would be seriously pushing it as far as airspace and breathing room for the port. I think you'd be better of with the same layout for 1 fifteen or 2 twelves. I've done this for several customers with great results.