As long as you're not using geardowns you should be fine, ausfs tiger has survived 10 years punishment in stock form. There's nothing wrong with the Tigers idler system, gearbox brace is a good upgrade though.

Ive found the first gears that tend to go are the brass ones closest to the chrome ones, that's only when I was using gear downs. The stock gearboxes without have always held up fine for me.