exhaust cans

what's the difference between having an oval shaped one vs. having a round one? I have heard that the oval ones slow down the exhaust flow because it is not a straight through flow (like the round ones). would this drastically affect your performance? Give you a better power band? change how it runs at different RPMs?

also, how do you know what to adjust your carbs to according to the pipe you have?

Oval or round has nothing to do with it being "straight through flow" that depends on weather your can is a race can(straight through baffle) or a street leagl can....

Ovals are generally a little smoother sounding because they can hold more packing than a round can.......