Not me, I'm expecting at least 5 years out of my A-50.
Exhaust can will not rust from outsidein 5 years. However, regular steel cans used by Kymco will rust immediately after you paint them, even if you use thermal-resistant paint in multiple coatings. Rusting is usually superficial and not in-depth.
However, the exhausts do burn from inside and usually after 25-30.000 kms you will notice a change in sound, meaning that internal chambers have been burnt and destroyed. Your mileage may vary, but usually after 25 and 50.000 kms it is time to replace exhaust on 4-stroke bikes and scoots.