I think rich would be the best person to get an answer from. I'm currently testing the prototype RV6 PCD/down pipe
I4 sorry :/Are you testing the V6 downpipe, because I know there's a separate thread for the I4 downpipe. I'm going to see what happens with the J-pipe first, then I may consider some mods to the down pipe. My one worry is that if you remove the down pipe cats, your going to overload the only cat left which may make it wear out faster. Maybe Im just being crazy.
Im actually considering wrapping the down pipes to take some heat away from the engine compartment now that I have a short ram intake.