You can do it if you can find a cap that will fit the threads and seal properly. Its been done, but I don't recall what thread size/pitch you need. Are you going to delete the EGR valve as well then?
ok...i cut the egr tube...i got a 1" copper(water) tube that is 1/2" round , took some plumber tape put the tube between where i cut the tube and used rubber cement to help seal...i hope it works....