Wesley Walden

I have a 2012 Silverado six speed transmission. It seems to shift very good but running about 40 - 45 on level ground, it's already made it's way to 6th gear. To me that doesn't seem normal. When speeding up, you can feel the torque convertor lock up and it pulls like it's suppose to. If you try to speed up a bit more aggressively, it will down shift to 5th gear. but 6th gear seems to high for 40 45 mph just looking for some thoughts on this Had a 88 IROC that did the same thing, ended up putting a trans go shift kit in it and solved the problem. Is there a upgrade for the 6 speed 2012 Silverado