I just picked up Cobb AP. I am running a skunk2 catback with a K&N airfilter and removed silencer. Can I safely run stage 2 with this setup? or should I wait for a up/dp? Also, can I run stage 2 with the third cat inplace?

 

to run a stage 2 you need a dp to take full advantage of the cobb ap stage 2. a up pipe is not necessary but will be better

 

I would wait for the down pipe b/c that is what cobbs stage 2 takes.

 

You need a DP for stage 2 but you can keep your 3rd cat. It will be a minimal decrease in power over a fully catless exhaust.