(No commercial relationship with Kooks Headers or Kooks Exotic)

I've had lots of experience with their Domestic headers and have them on some of my cars currently. However, anyone here have direct experience with their C63/S DP, either catted or uncatted?

They are currently 20% off.

 

I guess my questions would be: do you need a tune with these? As they have high flow green cats?

 

I've been on insta with them for the last hour and a half. You need a tune with these because the GESI cats are after the secondary O2 sensors and will still throw a cat efficiency error code. A tune is needed to turn off the cat efficiency test and check light. They are intended for those in States that require emission testing. They tried but the cats can't be packaged in the the OEM location. For states without sniffer tests, the catless are a better bet. They are around $1400 right now! Having purchased 5 Kooks headers in the last 10 years, this price point is a no brainer.