I am dumb let me start that off. If I buy a cat-back exhaust, does that mean that the exhaust comes with a catylic convertor, or does this mean that the exaust is installed behind the cat. If so where can I but a high flow cat to replace my stock convertor?

 

CAT BACK is the back muffler system.

You have to buy the high flow Catalytic Converter seperately.
RP web site.

 

what is the RP web site, I have a stock exhaust, and been thinking about replacing the catylic convertor with a midpipe. What do you think?

 

Cat back stands for catalytic convertor back. in other words, it is behind the catalytic converter and does not include that piece.

As for a catalytic convetor replacement. You have two choices. midpipe or hiflow catalytic converter. For a midpipe, you can get a B&B unit. gives good hp gains, but you won't pass emissions at all, & it will throw on your check engine light. Hi flow catalytic converters will not throw on the check engine light, and will pass emisions (if the guy doesn't realize it is not a stock piece). It tends to be a bit more expensive, and does not give as much hp as a straight midpipe. Right now, in the US the 2 big companies that make hi-flow cats. for the RX8 are RP performance & SR Motorsports. Both very good units.

 

Thanks