I don't undersatnd what you mean by mechanical bypass, but in the US several companies do this upgrades; what they do is: This upgrade will optimize the shift points, improve the shift feel, and improve the pressure rise, the transmission will run cooler and last longer. If you ship your valve body to their plant — they will incorporate the upgrades immediately and return it ready–to–install.
Fixes sloppy shifts, planetary burn up, band and clutch failures.
Lowers trans temperature for improved durability.
A must have for NOS, Turbo, and Supercharged machines.