I had a TRE Tranny with the double syncros. When it went I had Shindly rebuild it with the mitsu pieces. Had both pieces side by side and they looked the sam and worked the same. YMMV.
The syncros are the same as stock, but they sell a 'modified' second gear with their kit. All they do is cut an angle in the teeth of the second gear (right after the synchro) where the hub assembly slides onto to select second gear. So instead of being centerd like the stock gear it's offcentered kind of like this profile.
So let me get this right. TRE does some minor machining work and they use STOCK parts? Why would a person want to pay so much for something that is not much better. Or is this machining more intricit than i suspect? Is this something a guy with high mechanical skills could do on his own? I read this because i know 2nd gear syncs are horrible ( at least ive had bad luck) and i might want to replace it sometime. However, why not upgrade if i have to go in there anyways!?