the painted cylinders will run up to 40 degrees hotter than the non painted cylinders will because the pores have been sealed,but that's something they don't tell you when you get them painted like that,that's something they will only tell you if you ask!! another reason guys are having problems with the phenolic blocks !!!! it's alot easier to blame it on the manufacturer when actually a little info from the distributor would save a whole lot of stress for alot of guys who have the painted versions. proper cooling and lubrication is the whole key to longevity !!