If you live in CA aftermarket cats are not legal for installation on OBDII cars. Period. CARB does NOT recognize aftermarket catalytic converters as having the ability to add performance or fuel economy when compared to OEM equipment. You can call any of the high flow cat manufacturers and they'll tell you the same thing.
However if you're going to do anything I'm with 626- replace with high flow cats instead of straight pipes.

 

Well said.

Get high-flow cats or keep it stock—it's the right thing to do.

 

which cats did cheston post results for?

 

I believe it was R/T vs Straight Pipes vs Stock.

 

Well said gq-model-626.

Let's all be responsible enthusiasts.

 

good.. my post was at least somewhat helpful to everyone! Thanks for all the input guys!