VTT is the FSB voltage and while it is a "little" elevated at 1.35V the long term effect is probably negligible over the cpu lifespan, that said, if it will run stable at a lower VTT then by all means run it lower.
I'd be more concerned with the NB voltage at 1.66V, if possible try to get down to 1.5V or at the very minimum under 50°C for the NB chip
I don't think i could go any lower...cause when i run prime95 i am getting rounding errors. Unless rounding errors are something else besides vcore being low.