i cannt remember which tuner i was running for sure at the time of my first install. it was either the hypertech max energy or the superchips 3815. and no, no problems. you donnt need a tuner to use them.
and after you get them on, i would set the valve covers down on with no gasket and crank the motor over by hand and see if they hit the v/c's just to be safe i guess. okie has me worried now.lol. if they would happen to hit, which i donnt think they will, it would just be the baffle inside. easily fixed.
mileage isnt gonna matter that much in the helping department. they will help no matter the mileage.