It really depends of your dealer is mod friendly or not. I for one will not be modding my 370Z because of really bad experinces in the past.

Also, look up the Moss Warranty Act. It states if the dealer cannot come to the conclusion that the aftermarket part did not cause a malfunction in the car you are in the clear. But then again, it also depends on your dealer. I am going to stear clear from modifications so there goes any worries for me! :)

It's common sense. Would you warranty your product if your customers abuse or modify your product beyond it was designed for, causing the product to be none-functional?