I have a 5 year/60,000 mile warranty on my 03 Z, i bought it as an extended warranty, but i was wondering if i can do any upgrades to the car with out them saying that just voided your warranty?

 

Nope. Only if they can prove that the mod caused the issue.
Thay can't say: "No we won't replace your brakes cause of a custom exhaust"

They can say: "No we won't replace your engine because you put a turbo on it."