How bad would rectangular exhaust pipes hamper an engines flow?

 

i asked the same question with out much help ... but im working on trying it out just got to find the right size tubeing ... im thinking 1 1/2 in X 3 in. and making it a duel system ... im sure there will be a lot better clearace ... even thought of running it as a ground fx along under the door ... kinda of a side pipe skirt ... lol ... hope to hear others thoughts on this suject ... tao

 

Probably not all that much in a straight run. Getting it to turn a corner wouldn't be easy though.

 

Those 90 degree walls of the box tubing would cause extremely turbulent air, which would be extremely bad velocity, and thus tonnes of backpressure.

 

how about oval? I want to do dual exaust on my camaro and im trying to think of a way to get the most ground clearance

 

Oval would be better than square.

 

Oval would work. I too am looking at some 4" oval exhaust pipe that a local shop stocks.