I just got an email from my Akro supplier...FWIW.
Warning
We wish to inform You that more and more Akrapovic's products appear on different markets that are not sold via our regular distribution channels even counterfeited and therefore unable to profit from our standard warranty policy. In order to comply with the highest quality standards, all our products are equipped with the specific stamped code on the muffler inlet cap. The stamped code consists of a 3 digits. Products where such code fails, is even found removed or products that are subject to any, even visible, alternation will not enjoy the Company's warranty.
Warning
We wish to inform You that more and more Akrapovic's products appear on different markets that are not sold via our regular distribution channels even counterfeited and therefore unable to profit from our standard warranty policy. In order to comply with the highest quality standards, all our products are equipped with the specific stamped code on the muffler inlet cap. The stamped code consists of a 3 digits. Products where such code fails, is even found removed or products that are subject to any, even visible, alternation will not enjoy the Company's warranty.