an idea i toyed with for a while, but never really took that seriously was getting a set of used nascar side exit pipes. or "boom tubes". you can find them at
www.musclemotorsports.com, or at least you used to be able to. they are designed for low clearance and high flow obviously. depending on how it looks under the car, you can get a setup that has a pipe for each side, or they have the side exit pipe that both banks of cylenders feed into.
other than that, oval tubing tucked up in the driveshaft tunnel might work, although im not sure how id feel about it. thats alot of heat to tuck right up against the tranny and driveshaft, especially if youve upgraded to the aluminum one.
then theres always the sled pulling style pipes routed up through two big holes in the hood
throw a set of sparkplugs in the exhaust pipes, and rig up a flamethrower setup, could be fun. assuming you wont be driving on the street anyway.