Hey guys my xr8's started popping out of 5th when crusing along, what can cause this and what do i need to do? Any help of this would be great

Find a copy of this book and have a good read. It will help you to understand and diagnose the problem.

Or, take it to a gearbox shop.

My T5 is jummping out of 4th, from what I can understand it has to do with the syncros mainly the dog teeth, you can buy a rebuild kit from Malwood for $240 that replaces all the syncros and bearings, as long as the rest of the box is good this rebuild kit should fix it, or you could just buy the 5th gear syncro kit, but if you are pulling the gear box out and apart you might as well give it a birthday.