[Mike Burnham]

Chrome is acidic by nature. Acidic compuonds are subceptible to ionic compounds, and weathering. High temps can cause negative ions to adhear to the chrome faster. Static charge can cause positive ions to adhear to the chrome faster. Negetive ions cause yellowing. Positive ions cause blueing. Too rich of fuel mixture cause stitic charge to form in the pipes where moist unbuned fuel is flowing. Anytime you have moistour flowing in a pipe that is hot you gt this ionic convergence. On chrome it turns blue. By adjusting your fuel mixture you can reduce this affect.
Sorry if I lost anyone.