Dumping exhaust down under the car

While I got you guys attention. I also don’t want to dump underneath. I know it’s hard to get the exhaust to come out the back using 2.5“ pipes and extensions and going over the axles. Question is aren’t there smaller gas tanks that would fit that might not be as wide in order for the pipes to run along side? Don’t want to use a cell either. Anyone try it?
Sorry if I’m highjacking your post but thought it may be relevant.
Agree , hard to get 3 1/2" duals past a stock tank w/ offset spring hangars ! lol