shape of catalytic converters....

[chef]

Slaut, hi everyone, i was just thinking about this the other day, why do cats come in different shapes (aftermarket)? ....is it for fitment purposes? sound wise (tonality, more or less drone)? i mean in terms of flow, i don't think it'll make a difference if it's oval shape or cylindrical....right? just wanted to know if there was some scientific reasoning behind this...
thanks
fabs

[smokingslash]

I think its about the brand or like a copy right.
Some will flow better as one race cat I have ls hollow and the high flow is not