This is a very common mod on the Lil' Tex but from what I've read the results are iffy unless other mods are made to the auger speed, controller, etc.. For a reverse sear (did one last night on some pork chops) I use my old Traeger on "smoke" for about 45 minutes and it just sort of warms the meat up while pumping in a nice light smokiness, then I move the meat to GrillGrates on my Memphis fired up to 550 - 600. That's really the same thing mentioned above using a gasser to finish (my little Weber gasser won't get that hot).
Lots of folks mod their Traegers like crazy and some get fine results, but the original engineering of those cookers did not contemplate temps much over 400 and some mods might even be dangerous as a result. I love my old Traeger for what it is and what it does well, not for what I might wish it could do. I'd recommend leaving it alone unless you just want to have the fun of making a "project" out of it.
Hub