JAF publishes 2019 technical regulations.
http://jaf-sports.jp/cms_file/cms/cm...2841_00001.pdf
**JAF-GT300
3.1.3) Wheelbase
Vehicles with a wheelbase of 2,601 mm or more can be extended up to 2%. (2018 regulation admitted up to 1%)
In this case, extension of the wheel base must be carried out by adjusting the position of the axle before the A pillar and / or behind the C pillar.
3.3.3.2) Opening of fender
The term "air after brake cooling" changed to the term "air in the wheelhouse."
3.3.7) Flat bottom, Floor
In order to equalize performance, JAF can change the thickness of the spacer with prior notice even during the season.
5.1) Engine type and position
Only the way of regulation has been changed.
The Grandfather rule that it is possible to change the engine mounting position of vehicles manufactured before 2016 was deleted. (In a word, Prius GT can't run in 2019.)
5.3.1.3) Engine with supercharging device
Installation of the air restrictor is exempted only when supercharging pressure limit is implemented.
**JAF-GT300MC
3.3.3.2) Opening of fender
The term "air after brake cooling" changed to the term "air in the wheelhouse."
3.3.7) Flat bottom, Floor
In order to equalize performance, JAF can change the thickness of the spacer with prior notice even during the season.
3.3.18) Reinforce
The provision that processing and changing of roll cage is possible if JAF permission is made was deleted.
5.2) Engine position
Only the way of regulation has been changed.