the studs are 13.80 retail from nissan. and then theres the nuts. about the same.(same as sr20) the 500 dollar price comes from havint to remove the manifold ie r and r the turbo.
then drill and easy-out the studs. if there broken off. also if a few are broken youd be retarded not to repl;ace them all.
so that price is just realistic. two solid days is abit excesive. but 1 day is believable.