If you use the castle link, set it to auto lipo and then you can adjust the LVC to 3v - 3.7v per cell. 3.5 is kinda high. I run all mine at 3.3v. This is still higher than the recommended setting for most lipos.
The best upgrades IMO are the Variable Dampening Piston kit and the RPM true trac kit for the rear. Also for good batteries with long runtime go with SPC 2s 8000mah. They are the best bang for the buck.