Sonic Generations - S Ranks & No Skills - Part 002: Chemical Plant Zone

Act 1 feels quite similar to Act 1 of Sonic 2's Chemical Plant. Blue Balls, alternate routes and all. Keep above water for as long as possible when going for an S Rank. That applies for both Acts.
Act 2 adds a few more mechanics. Drfiting around corners very early on and free falling. Whilst Free Falling, you can boost to descend quicker. Act 2 has more opportunities to fall into the "water", messing your run up more. This also introduce cannon like objects you have to shoot yourself out of in a certain direction (in this case to the right). Nailing the mid-air boost at 4:55 saves time as well, as long as you don't overshoot it. Landing on the rail is perfect, but anything just before helps too.
Finishing this act saves Amy Rose and Sonic kind of regrets that instantly.