Zach, PM me on the exact specs of your FMIC setup. I know a wholesaler, and I can get 3 or 4 ply silicon couplers for 60% cheaper than what is out there with Turbohoses.com or anything else. How thick of a core do you want? And why 18" wide? THats tiny!!! I can get you a core thats about 25in wide, 6 or 7 in tall, and 2.5" thick, with 2.5" inlets/outlets for like $130.
I can also get Tbolt Clamps, but the piping part will be hard to figure out, since there is no bolt on FMIC kit for the IS.