Has anyone increased the exhaust pipe diameter

[mazdamp3_18]

I wanted to know if anyone has increased the diameter of the exhaust and kept the racing beat exhaust. I am planning on doing this and i want to know about the sound change and the effectiveness of this mod and if it is even worth it. Should i have the 2nd cat and the resonator removed or just the resonator or neither?
thanks for any help...

Chris
Vivid Yellow MP3

 

[toolman24594]

I had my resonator removed , a little difference but not much, it's a little deeper sound to it though.