I really think getting the 20" Seat alloy is a big mistake, the car simply doesn't need it and it will only decrease the performance of the car.
The 20 x 8 is also 1" wider than the 19 x 7 so that's a lot more alloy on each wheel,
Unfortunately 235x50R19 that comes with the 19" are also slightly too big for the the 19" I reckon it should be 215x55R19 for the sweet spot and it will also look and fit better on a 7" wide tyre rim.
Safe your money and don't get the 20" and get the 19" instead.
The 20 x 8 is also 1" wider than the 19 x 7 so that's a lot more alloy on each wheel,
Unfortunately 235x50R19 that comes with the 19" are also slightly too big for the the 19" I reckon it should be 215x55R19 for the sweet spot and it will also look and fit better on a 7" wide tyre rim.
Safe your money and don't get the 20" and get the 19" instead.