If you can find a shop that will turn the rotors on your vehicle that would be my suggestion. No labor of R&R that way. And the rotor is true to your spindle that way.
Always remember - you get what you pay for. A $40 slotted rotor seems low to me. I'd wonder how well they hold up under an aggressive pad (assuming you are putting on a superior brake if you are considering a slotted rotor). If not increasing brake pad performance, no need to change rotors unless yours are beyond repair.
That is of course my opinion. I've never felt that a stock vehicle required slotted rotors, and especially not if you have an average pad.
Always remember - you get what you pay for. A $40 slotted rotor seems low to me. I'd wonder how well they hold up under an aggressive pad (assuming you are putting on a superior brake if you are considering a slotted rotor). If not increasing brake pad performance, no need to change rotors unless yours are beyond repair.
That is of course my opinion. I've never felt that a stock vehicle required slotted rotors, and especially not if you have an average pad.