I wanted to have the ducts be CEET but I found with the complex curves from the heater core to the mixer chambers and to the windshield defog it was not going to be easy. It seems the duct length cuts recommended include the aluminum duct fittings instead of the just the ducts. No biggie. TAF only sent me one side of the 80mm ducting to the mixer but it is close enough to 3 inches that I can make it work. Gotta love SIKA ..