Improved Jump Jet
A modern refinement upon the centuries old design of standard jump jets, improved jump jets are twice as large and as heavy as their normal counterparts, but can propel a 'Mech further with less heat build-up.
Developed by Clan Wolf-in-Exile in 3069,  thanks to their sharing of the specs with allies of the Arc-Royal Defense Cordon fighting against the Blakists and the espionage efforts of their Crusader brethren, they have spread throughout the Inner Sphere.
Improved Jump Jets take up two critical slots each and are twice the mass of standard jump jets, but allow the 'Mech's maximum jumping MP to equal its running MP. Additionally, Improved Jump Jets produce half the heat of standard models, at one heat point per 2 hexes jumped, with a minimum of 3 heat points.
- TechManual, pp. 225-226, Improved Jump Jets