First - while I love my Supra board brethren, you guys have some real audio nuts and true experts over here.

I need to build a sub enclosure for a Polk MM1240 to be mounted in the typical driver foot well location of a Supra Saltare. It's gotta be a sealed box - I don't have room for a properly ported box down there, plus I prefer tight bass over loud. If it matters, I've got max rated wattage available.

Polk specs call for 0.88 cu. ft. (1520 cu. in.) and list overall external dimensions of 13.5"x18"x10" (using 3/4" material) - that won't fit. The best volume match I can come up with that fits is 14"x15"x10.5". Will this more cubic geometry have any negative effects on performance?

Also, do you guys generally put some type of spacers or feet on the bottom to allow things to dry out underneath?

Finally, a question on crossover points. The sub is rated at 22-200Hz, the mating cabins are 6.5" MM651's rated at 40-25k, and the towers are 6"x9" MM691's rated at 30-25k (and have a separate built in crossover). What would be a good starting point for crossover points for the sub, cabins, & towers?

Thanks, I'll hang up and listen...