No, it does not. Even when you are accelerated by the gravity of a planet your speed maxes out at 104 m/s. You can easily check that by creating a new game with the "Star System" scenario which puts you into a lander free-falling towards the surface of a planet.
By the way, you can change the speed yourself without using mods by editing the file
SpaceEngineers\Content\Data\Environment.sbc with a text editor. Just change the number 100 in these two lines to your liking:
Unfortunately every weekly update might overwrite your changes.