TRE originally started started installing double springs on the 1st/2nd hub sleeve assemblies in 1989 before we were even a shop.  This was first done to my 85 Colt Turbo GTS and then later to my 89 Colt Turbo & GVR4 and Ming's 92AWD. Doubling of the springs worked pretty good but the factory springs still jump out of the synchro keys if the clutch was being dumped too aggressively, they just don't have enough tension. This is a big problem on the larger high-capacity 3rd/4th gearset that was used from 93-99 and sometimes on the 1st/2nd hub/sleeves. In 2002 TRE started installing their own synchro key springs on 1st/2nd and the larger high-capacity 3rd/4th hub & sleeve.  The springs have twice the tension of the factory springs and they don't jump out of the keys like the factory springs, doubled up or not. No need to stretch the factory springs, no need to cut the end off the spring to keep them from breaking as these springs will outlast anything we've seen.