You might need to go up to the .300 shafts with the extra weight in the front. I shoot almost the same set up and the .340 shafts were weaker then what I would've liked. Going up to the .300s will add several grains as it is.
Grab six and run the FACT weight system GT offers. Do you need more weight? Probably not. But if you want more go for it. The FACT will let you play with it to see what's best without being a major pita. Or grab a 3 pack of 125gr heads and see if you notice a difference.
My last pair of 980s lasted 8 seasons before the uppers were to worn out to support. I picked up a pair of the Cougars for August. Not as stiff as I would like and will be getting another pair of the 980s.