I had this same issue for a while. I already had a FMIC and just needed piping. I finally just sold the FMIC and bought the Hybrid kit for the RB25DET from
http://www.240supply.com
They added the hangers for the S13, so it bolted right up. I had to make one custom bracket, but you could get away with not using it.It was only around $700 for the IC/piping/shipping. I am very happy with it. It is a huge IC.