They can't void the warranty on your gas tank because you modified your engine slightly. It's part of the Magnossun Moss act.
What they can do is make a note of the modifications on your car when you bring it in. If you bring it in later down the road for an engine issue they can say; "On this date when your car was returned for service you had these engine modifiers on your car. These modifiers are what broke your engine."
They have to prove that whatever you did caused the engine parts to break but it usually takes a courtroom to get them to do that.
What they can do is make a note of the modifications on your car when you bring it in. If you bring it in later down the road for an engine issue they can say; "On this date when your car was returned for service you had these engine modifiers on your car. These modifiers are what broke your engine."
They have to prove that whatever you did caused the engine parts to break but it usually takes a courtroom to get them to do that.
