Same upgrade issue I had here. During the intro 1st year promo I went with 100mpbs and had the max 16 channel modem. I was getting 90mpbs. I then remembered that my router was only had 10/100 wired and after upgrading to a gigabit, I got 126mpbs. I wasn't complaining!
My problem became upgrading long 40ft LAN cables and the wireless cards in my laptops. Although they were wireless N 300, then only supported 2.4G and that frequency even with the best WiFi routers benchmarked off smallnetbuilder top off in the ~150mpbs with an ideal lab environment signal. Realistically where the laptops spend most of their time, 60mbps was realistic.
After the year promo expired, I signed up for 50mpbs, with the 16 channel modem I was benchmarking 58mpbs. After Time Warner got bought by Spectrum, speeds jumped up to 70mpbs... which I feel is the perfect speed for home taking into account the realistic typical home wireless speeds. If you want faster speed, connect wired.
By the way, if you ISP supports the same modems, I am beyond happy with the Netgear CM500 (16 channel) and CM600 (24). I also had no issues with Motorola/Arris SB6183 (16).... but those had IPV6 and security issues that were patched recently. Those also have ridiculously bright LEDs that some can use as a night light. Seriously bright.