A 2.5l Phase I will plug and play with either your ECU or the 2.5l ECU. That's 97-99 legacy/outback, 98 RS, 98 forester.
The 99 2.2l is Phase II it will require a few changes for MAF/MAP and crank sensor etc. It has been covered in this forum before if you search back a couple of years.
The JDM stuff will cost you much more than $1000 to do properly.