Strarter Problem

[oneba87lx]

My car will start fine when it's cold, but once it gets up to operating tempature it is very hard to start. And sometimes it won't start until its cooled down. I can hear the starting trying to turn the motor.I replaced the starter within the last 2 yrs. I thought it last a liitle than it has. Maybe my headers cause additional heat and this shortens the life of my starter. Any ideas would be greatly appreaciated.