I'm going to replace my ETS Open dump downpipe and Race catless test pipe with ETS recirculated downpipe and ETS high flow Cat pipe. Do I need to do tuning or nothing bad is going to happen if I don't?
Because I can replace it in any muffler shop where if I need to tune it I need to go to special one.

 

That's a big change in exhaust flow. Will be ok to cruise around on, but will likely be off running WOT, I would recommend a tune..

 

your going to be a little rich depends on what you can tolerate. Nothings going to blow so it just become a mild performance/mileage thing.

 

Thank you. I went to local tuning place and did a dyno run to see what I have now. They said that turning is not really required after the downgrade. I'll do another dyno afterwards. They said that most likely I'm not going to see HP decrease, only AFR will be different

 

what about changes with exhaust? I'm moving from a ets extreme to a tomei catback. Not sure if i need a retune

 

OP: At the very least, do some logs after the change. I'm sure you'd run a little more rich after the swap over. Always best to have it checked after any kind of change.