I am working with the evil one to see what i can do about the exhaust. essentially i have two exhaust ducts that are 6.5" in diameter each flowing about 800CFM of 1200F air. if i go in a front engine configuration the exhaust routing gets more complicated.
I've idly thought about making a turbine-electric hybrid just for fun and for the exhaust I'm thinking of using the venturi effect.
Route the exhaust under the car, increasing the cross sectional area while flattening out the pipe. Sandwich that between two heat shields which are perforated with hot rod louvers, smooth out and humps in. After a foot or so of louvers put louvers in the exhaust pipe, smooth in, humps out.
Between the increase in the cross sectional area and mixing the outside air with the exhaust, it should be plenty cool by the end of the pipes.
Add in some rake and low clearance side valances and you'll get a good boost in downforce too.
If that seems like too much, route the exhaust to a turbo or two, connect the outlet of the first side to an intercooler and then into the inlet of the second side and you'll have an air cycle AC system like found in turbine powered aircraft.