An FMIC will be larger than the heat exchanger for a liquid cooled setup. If the heat exchanger won't fit, and FMIC will certainly not fit. However, I think you're mistaken. With enough time and effort, you can make a heat exchanger fit just about any car.

 

Yeah, the kit I linked to may not work for RD's at all, but it's a start for ideas.

 

yeah heat exchangers, even a real big one is smaller than most FMICs you will see out there..

you can fit a pretty big intercooler on a tib, and heat exchangers are usually smaller than a normal sized intercooler. and theres more room for a heat exchanger cuz you don't have the piping to deal with..

the intercoolers i use in my turbo kits are 21x6x2.5" core and there is plenty of room.. could go with a 21x6x2.5" core heat exchanger easily and even go another 3-4" or so wider and a couple inches taller if you wanted..

 

You could, if you had the skills and cash, use a FMIC with a roots blower setup. I've seen it done. You modify the manifold after the blower to have an input and output that connects to the FMIC. So it would like like the below rough sketch.

___________
from FMIC -----> | \ |
| \ | -------> to FMIC
|______\___|