Please help

I recently purchased an underdrive crank pulley from speedfreaks racing and im having trouble taking off my factory pulley if anyone has done this mod and can give advice that would be awesome. A 1/2 inch impact wont turn the bolt and a 3 foot strong arm just rotates the pulley has anyone else had this problem when trying to remove their factory under drive crank pulley?
LOKI

ok finnaly got it off... who ever put on my pulley should be shot with their own ball of shit... It took a 3/4 inch impact but I finnaly got it. If anyone plans on doing this mod and has trouble give me a shout and ill be glad to help out with a couple pointers I learned along the way.

glad you got in taken care of