This will do GREAT amounts of good over a FMIC IF you keep the temps in the tank down all the time. If you don't mind putting icewater in there every few hours while your racing. Go for it.
Just a side note, the Water IC will suck balls if you don't keep the water cool. In other words, worse then an FMIC because there's no direct air hitting it, and where it's located, it's in direct exposure to engine heat.