pi314159265358978 | 16w40a (ONLY): Technically 398 m/s (I couldn't resist) @pi314159265358978 | Uploaded 8 years ago | Updated 2 minutes ago
Well, that's the 16W40A for ya. (10252*sqrt(2))/(46.733-10.317) = 398.1
Thanks to ilmango for suggesting the armor stand method of getting 1 tick delay and also big thanks to Spire for his excellent explanation of this phenomenon (Which can be found in the comment section of his video. Highly recommended reading it).
My previous design (320 m/s):
youtube.com/watch?v=nsxWTlGlLF8
My first design (320 m/s):
youtube.com/watch?v=hvmHTGQSW6k
Comparison with a boat accelerator from 1.9 snapshots (340 m/s):
youtube.com/watch?v=voJA7xEsVuw
EDDxample's design (280 m/s):
youtube.com/watch?v=0DPKkmfvWfE
RedstoneSpire's design (320 m/s):
youtube.com/watch?v=lvCcJu-0Nus
TBRIANANDY1's design (~120 m/s):
youtube.com/watch?v=GzOzMFW8tqM

World Download: http://www.mediafire.com/file/i6h2k4c5otnjoa1/Mesa+Tests+3.zip