Not sure. Dealer told me when I bought it that it was not possible but not sure how informed they are.
I have 2 inch spacers on mine (XR4145HC). They were well worth the investment. At the time, my dealer confirmed with LS that putting spacers on would not affect the warranty. I bought third party spacers.
Also, a regen every 15 hours sounds like a lot. What RPM do you usually run the engine? If I run around 1,500 - 1,800 RPM, I get a regen every 20'ish hours. If I bump my RPM up and always run at 2,200+ RPM, I only regen every 50 hours, and that is only because if it hasn't sensed the need for a regen after 50 hours, it will automatically force one.