I've got 3" decat DP and I was thinking to change cat back, but there's sports cat in the mid section so does it have to be mapped again? decat DP will stay as it is now, I'd only change mid section and BB.
Thanks

 

sure its a sports cat not a resonator?

 

Yes, it's a Milltek hi-flow cat and resonator is further down.

 

needs to check afr's, one of those could be ok, could not be

 

Does it actually will be affected if the cat is fitted after two lambdas not between them like when you have cat in the DP.