First post, yay! First of all a big thank you to everyone working on the mod, i've really been enjoying it! Keep it up!

Down to business:
When trying to reach the top speed in the high speed trains i came across a bug.

Once the speed of +/- 220 km/h is exceeded the train locks itself in max speed. Slowing down is no longer possible. Speedometer rapidly changes between 237/473 in the HST and between 279/559 in the ICB.

Using Traincraft 4.4.1_021

longer sets of weaker tracks from railcraft, or unpowered booster track, should slow it back down.
the issue has been around since 1.6.4 and I've never figured out what it was, so at this point it's safe to say it won't be getting fixed until the rewrite.

No worries! Indeed, the unpowered booster track is a good solution for now. Or simply not going any faster than 200km/h. Cheers!