I had my 450 loaded with the hot damn tune, Low Boost Fuel on level 3, and towed 18 K. No sweating. EGTs were in check, unless I was on a very steep grade, I never saw more than 1200. Spiked to 1350 a few times on the longer grades, but only for a few seconds. Now, keep in mind, I have 4.30 gears.... if you are running 3.73 or even 3.55s..... you are gonna get hot.