Looks like a healthy combo.
http://www.5speeds.com/t5.htm

 

If you get the G Force upgraded gears and mainshaft, you shouldn't need the retainer.....not sure if it would fit with the wider gears anyway. I'd give them a call to see if you need it first....just my 2 cents...

 

I received a reply from the 5speed.com guys and they said they use the same gears as gforce (check their webpage) and all their t5's get this billit stabilizer so I know it fits.
I'm an over kill kind of guy. I think this and the gears should keep me sleeping at night.
Now it's just a matter of dog ring or not and what 5th gear to choose.

 

I could have a stabilizer too then, and don't know it! I had the whole tranny built by G-Force but haven't opened it up to look. .....And I don't plan on looking unless I have to.

BTW - Don't know if this will help, but I chose the .59 ratio 5th gear and it made a world of difference on the highway...with 3.73:1 rear, my rpm's are 1800 at 70 MPH.

With the stock T-5, it ran around 2300 at 70!!

 

5speed.com installs g-force gears using 5speed.com stabilizers. I've been in contact with them and they will get back to me on rebuild costs including bronze shift forks and the ASTM 4340-300M Thru Hard Premium Alloy mainshaft upgrades.

If I ever hear back from g-force I'll ask them if they install this stabilizer from 5speed.com.

 

Wow. It seems you must be running one healthy motor there. Is it in excess of 600 HP and TQ???

Mine is rated at that, so I have no problem sleeping at night....-

-Then again I'm not an "Overkill" kind of guy as you said you are.....good luck!

 

All that the rear countergear bearing retainer does, is protect against high loading in 5th gear. If you don't road race your car at top speed it's probably not an issue.

The weakest part of these transmissions is the case. It flexes and stretches across the front, which allows the clutch gear and countergear to move apart, which mis-aligns the teeth, which causes rapid and total failure. The Gearzone retainer doesn't help that.

Seems to me you could put gears in there made of 99% pure nonobtanium forged in the fiery furnaces of Hell by 10,000 year old gnomes, alloyed with a mere 1% of irreplacium for added harmonic suppression; and the case would still stretch and the gears would still tear up if you beat on it enough. But I don't know that for sure, that's just a guess.