It may be interesting to note that I fired it up for a few seconds with NO mufflers in the middle of the swap and was expecting some serious open pipe mayhem like my old sporty with drag pipes but was surprised that it sounded really lame. For a moment there I thought something was really wrong then I realized, all the beautiful music was choked down to nothing by the catalytic converter!!
Ya know, when I swapped my header pipe to cat free a couple of months ago, I fired it up for a second or two before I put the mufflers back on just to hear how loud it would be, and it wasn't loud at all. I was expecting ear shattering goodness and maybe a flame or two shooting out. Man, was I disappointed. But it obviously wasn't being choked out by the cats, since I was now catless.