I recently both of the gauges. I mounted the FJO control box under the main relay/fuse box at the right-front engine bay, I only used 3 screws. Used the front O2 bung in the downpipe. I removed the wire pins from the meter connector and feed the cable through the right firewall grommet, reassembled the connector, and hooked it up. The power cable was also fed through that grommet. You didn't say what year your car is, if you need help "tricking" the ECU with a missing downcat O2 sensor let me know.
The EGT probe can be can be mounted in the front manifold. If you loosen the heat shields, they can be positiond out of the way to drill a hole. I used a number of drills starting with 3/32" and worked up to the "R" drill for a 1/8" MNPT tap( if that is what you have). I coat the drill in grease to collect metal bits and shavings from drilling, same thing for the tap. There is enough metal thinkness in the mahifold to tap for the fitting. You will also need to drill a hole in the heat shield. After drilling the manifold, locate where the hole in tha manifold needs to be, put a piece of wood between the manfold and shield, and drill the hole. I used a 3/4 hole saw. A number of others have drilled into the manifold at the same place, I also checked around.
Jeff