255 mph

[Duplode]

Why is the absolute top speed only 245 instead of 255? The latter one would be more logical...

It is a hard-coded limit in the speed-updating routine (confirmed via restunts). I suspect Pickell set an arbitrary cap so that the physics engine wouldn't become (too) wacky. IIRC I read somewhere here that one of the later ports of Stunts (maybe Amiga or FM Towns) has 256mph as the limit speed, which suggests that after some bugs were fixed it became feasible to remove the restriction.

(is there a way to unlock this speed limit?)

Patching the .exe to change the limit value might just work. I wonder why I haven't tried it yet 

[dreadnaut]

I've seen 255 as maximum speed in BB1.1 —crashing in powergear sometimes, including ZCT144.

[CTG]

I've seen 255 as maximum speed in BB1.1 —crashing in powergear sometimes, including ZCT144.

That's only a mistake, as you can read on the first page.