With large turbo upgrades or running high boost, an FMIC is a necessity.  The stock top-mount intercooler was designed for very mild boost levels; anything over 10 psi is pushing it's capacity.  Remember the Zenki FC3S is running 5.5 psi of stock boost; the Kouki FC3S is running 7.5 psi of stock boost.  There are several FMIC kits available, or you can make your own FMIC kit from scratch.  Be aware that most complete FMIC kits are pretty pricey and usually at least $1,000!  One aftermarket FMIC kit to note is the new GReddy V-Spec SPL kit for the FC3S.  Priced around $1,000, it comes complete with everything you need for installation.  The only bad thing I heard about this kit is that it needs minor custom work to fit with power steering; if you have no power steering, you should have no problem.

If you decide on making your own intercooler kit, intercooler cores can be bought from XS Engineering or Turbonetics/Spearco.  You'll need to be able to get the endtanks TIG welded due to the aluminum construction.  Cast endtanks are also available from those vendors.

Down to the nitty fritty of intercooler core design...  There are three things that are important about intercoler core design:
Efficiency:   how well the intercooler core works in getting rid of heat; the efficiency curves are tied into how much air flows through the outside of the core itself (usually represented at vehicle speed in MPH).
Pressure Drop:   measured as how much intake charge pressure is lost going through the inside of the core as measured in "psi".
Flow Rate:   maximum amount of intake charge air flow the inside core can handle at any one time

Spearco has a very nice pamphlet out on more details on intercooler and intercooler design.  If you want more info on intercoolers, All About Intercooling by George Spears is available from Turbonetics on their website for $10.00.
Click here to go to the Spearco Intercooler website!

One of the real secret of intecooler core design is internal fin design.  Efficiency and pressure drop are affect depending on how the internals fins are configured within the core.  A lot of the Japanese manufacturers if FMIC kits offer different types of FMIC internal fin designs.  For example, GReddy intercoolers offer a V-Spec and an R-Spec intercooler; the only difference is the internal fin design - the V-spec has less pressure drop, but the R-Spec has better efficiency.  This is solely due to internal fin design of the intercooler core.

By making sure the intercooler can handle your turbo and the amount of boost you're running, this ensures your potential intercooler (core) isn't holding you back in performance!  With the potential of a lot of the full turbo upgrades available to the FC, there's not reason the run the biggest intercooler you can fit and afford up front...

Questions?  Comments?  Send mail to:  reted@fc3spro.com