I have 30k miles on my Z and I recently bought some Hawks HPS brake pads. I came across the feeling that I should machine the rotors but when I browse through the internet there are mixed reviews. Since I am changing the brake pads I might as well take out the rotors while I am there and send it to the shop to be machined. I need opinions as far as machining because I know in order for them to smooth things out they will either take just enough or too much off the rotor bringing it closer to the minimum clearances advised in the manual.

 

Some rotors take to machining fine others do not. Most ,but not all of the japaneese ones, do not last very long after they are turned.

I would buy new ones because if after you cut them and they may start to warp you're going to have to buy new pads again.

 

try to get a shop to do a runout measurement on your rotors. IMO, if they ain't warped (runout greater than spec) and you have no problems, it is a waste of metal as you pointed out. You have 22 mm of thickness to play with. If there is zero runout, you should be fine as is.

I had mine resurfaced when I went to all metal pads, just for the sake of getting a good wear pattern established with the new pads. However, I have been going back and forth from stock to my Metal Matrix pads on a regular basis without remachining them with zero problem.