I've been running a 7lb cap for about the last 3-4 months and have had zero issues with temps. I have an Auber Instruments digital gauge using their temp probe and notice my temps are maybe a few degrees higher but negligible if at all. I don't tow heavy uphill in 100 degree plus weather so YMMV, but I feel that taking some strain off the cooling system can only be a net positive. This was recommended to me a while back by the late Towcat.