The 270 is a 7870 with a slight speed boost, so I don't think you will see that much of an improvement. It depends on the games and settings of course, the 1050 ti has 4gb of memory so that can make a difference in some games. If it were me I wouldn't spend the money on anything less than an RX 470 or 1060 3gb. That's really what would be a step up for you, a 1050 ti is ~$140 but it's not going to give you $140 of extra performance over your 270.