Ive been using the TR-6s for over a year now, with no problems. I have a 8# lower with a race tune for also over a year now. Any changes in pulley creates more heat. Now on a daily driver I see no difference, you wont be at max bosst all the time. Most of the people here go by what they hear, not what they have experienced. Even a 4# pulley can mess up your motor, its all in the tune.