Vibrating can also be caused by a crack in the rotors surface.
It turns out that drilling and slotting either give a place for water to evacuate like the tread on a tire, or allows steam to gas through kind of like what drilling was intended for.
See cross-drilled rotors myth ).
On the street, drilled rotors are ok, but can create noise.
Surprisingly, I have placed a dial indicator on so-called warped rotors to find that they have no run-out what-so-ever, and also, on new rotors that have run-out but dont produce any pulsing.Many people have such strong convictions about rotor warping that they wont believe anything I say in this post.What does happen is that the layer of pad material on the rotor surface builds up unevenly, and also, the metallurgy of the rotor can change states.There is different levels of cross-drilling.Many people and advertisements claim that cross drilling helps the rotor cool.Slotting is also advertised to wipe the surface of the pad preventing glazing.This should not be interpreted as a shorter stopping distance.Rotors do tend to have run-out even when new, but you would never know it as long as the run-out is in tolerance; so, dont mistake some run-out for warping when the rotor had it from the day it was installed and when the pulsations.The worst situation is when a crack forms and connects between multiple holes much like a connect-the-dot puzzle.Even if there was a small area left after resurfacing, that one raj patel poker spot will create a hot spot which will grow in fairly short order.But this seems to be only temporary and when the rotor cools, it returns to its normal flat state.

I dont see how slotting is going to prevent this.
So you have your heart set on one of those new big brake kit upgrades for your street ride.
Just pick up the phone and give us a ring.
If you have a vibration that only appears during hard or extended braking, it may be a crack.Big brake systems dont decrease your cars stopping distance over stock.This can lead to a large piece of the rotor breaking free which I can assure you is not good at all.The reason for this is that the cracks opens up when the rotor is hot and closes when its cold.I have even mistaken this vibration as my tires being out of balance.So now that you know that there is no benefit to running a cross drilled rotor, we are left with a major disadvantage.When run on cars that wont see the track, you can run cross-drilled rotors and not have to worry about the cracking mentioned above, because on the street your vehicle wont generate enough heat to crack them.If I have my rotors resurfaced, will that fix the problem?Furthermore, any benefit of extra cooling is most likely off set by the reduction of the rotors mass due to the drilling which lowers the overall heat capacity of the rotor.