First, I want to start by saying I absolutely LOVE my Grill Grates(TM). They're awesome but as the company's website will tell you, they do raise the temperature of your grill significantly.
So here's my story . . . a couple of years back the porcelain coated grates that came with my Weber Genesis rotted so I tossed them and bought a full replacement kit of Grill Grates(TM). Occasionally, I've turned up the gas all the way to let the grease burn off but after a while I noticed that the cook box of my grill started to warp. The front edge began to bow out so that the lid did not fit over it correctly. Luckily, the folks at Weber were nice enough to send me a new cook box, but I'm swapping half of my Grill Grates with a buddy for half of their stainless steel Weber grates. Hopefully, that should keep the temps down enough so that the cook box doesn't get damaged again.