When they see the heads on bolts and nuts are warn in places where they didn't work, they will know someone other then subaru worked on the car...... It's not hard to tell when people have worked on a car. Since it was under warranty, noone should have touched the car in places where it has not been worked on by subaru. They can look through their records, see what they've worked on, and tell you that you're car is no longer covered under warranty because someone else worked on it. Mechanics know what's up. I've heard of this happenning b4, lots of times. Like I said, people are lucky subaru doesn't make a habbit of sicking their lawyers on people. It would probably be better to leave the mods on an if they say anything argue that the mods have nothing to do with the broken part... That's just my opinion thought.not that i advocate defrauding, but, how will subaru ever know it was changed back to stock?