It`s better check whole maps of compressor wheels than to compare AR only. Turbine side either 25 & 28 absolutely same, but compressor wheels are different. 28R will provide more boost for sure, but for 1300cc I`d better prefer GT25R. But if you are planning to change pistons, connecting rods etc. then to shift the red line up to 8000, in this case - 28R will be ok.
You could check map and compare pressure ratio, it`s self explanatory.
Waiting for new 1/4 miles results