stage-3 chip for a 2019 Sierra Duramax
I purchased the stage-3 chip for a 2019 GMC Sierra with the Duramax diesel engine. I sent a video of my install to CYC via email to assure I had done it correctly - CYC Chat replied and confirmed that it was installed correctly. I asked, via Chat, what I could realistically expect, for my specific vehicle, in improved mileage. Chat told me to expect between 4-6 MPG better fuel mileage. My average mileage before I installed the chip was 19.6 MPG. My average MPG after driving 567.2 miles with the chip was actually worse at 19.4 (I reset the odometer after the first 150 miles as suggested by CYC). After a little back and forth (Chat "suggested" I may have been drag racing) CYC gave me a Return Autorization Number and I shipped it back to them. I received a refund, minus the restocking fee, as I expected. Be sure to document your installation and have all communications via Chat or email, well within their 30-day guarantee window. While Chat was overall timely and professional their product did not work for my vehicle.