Thanks you very much Loukas ! I had a look and it looks good but you must remember that you will need two of those kits for the NSR so you are looking at 900EUR/$1300 where the tyga kit is $1400 for the normal head kit.

Then there's three other problems, possible four.

1. Looks like the water hoses will connect differently.
2. You will need to make some flanges for your pipes.
3. Will NSR125 barrels fit on the 250's case ? Im not too sure about this.
4. I dont think the power valves will have the right brackets and cables ?

Sure if you really want you can make it work...but at only $100 differance between a bolt on kit...well its up to you !