What should I do if the new LaVida exhaust pipe rusts

For the question you asked, it may be because the mixture can't burn completely in the combustion chamber when the engine is idling, which leads to the sudden abnormal sound of the exhaust pipe, or it may be caused by too much carbon deposition in the throttle and intake. Due to too much carbon and dirt deposited in the air inlet, the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake, resulting in too rich or too lean mixture, abnormal combustion or engine jitter or even failure to start after starting. It is best to check the intake valve and combustion chamber for excessive carbon deposition with an endoscope. I hope my answer is helpful to you.