Go ahead and fit it and get the apexi mapped to suit, id imagine the vf28 would be faster spooling than vf35, wont be much in it either ways and with type r gearing it wont be any issue anyway.
Not sure what you have done to car at moment, but if car is standard.. i would defo hold off the map and gather up all the bits like your turbo, decat, walbro pump, decent panel filter and plugs, and bang them all on the car at one time and get mapped next day, and you will be in for a real treat when its all done as a package. Good luck with her.