i keep reading and reading about this "tre" but have yet to figure out what it is??????

In case you can't read Hub-ese, a TRE is often used to remove the decel backfire (pop) that comes when you put an aftermarket FULL exhaust system on without a cat(s).

The side effect is you lose your dash gear indicator, which will henceforth always show 6.

To avoid that, most people don't install a TRE and plug the PAIR valve and try to tune the map in the piggy to lessen the decel pop.

HealTech developed an A-TRE, which is the same as a tre, but it has a gear indicator pod you can put up where you can see it. Some people, like me, want to see what gear we are in.

I just don't know how I ever got along without a gear indicator display, in the almost 40 years I rode without one.