Today I went to replace my old iPhone 6 charging cord that was starting to come apart at the lightning end. Grabbed the cord out of my iPhone 7 Plus box and noticed it's much thicker than the old one. Being curious I did some charging tests with a USB inline current meter. With my phone down to about 60% charge the old cord would charge at 1.3A (6.5W) and the new cord charges at 1.6A (8W). So looks like older lightning cords will slow down the charging speed compared to what Apple is currently shipping. Figured I would share my findings as I searched first but didn't find the answer I was looking for. PS. As a side note, kind of interesting that iPhones still ship with a 5W wall charger. They should toss the 12W ipad adapter into the phone boxes. But that's a different topic all together.