2v heads have a teardrop shaped intake port. 96-98 4v heads had 2 sets of intake ports, while 99+ 4v heads have more of an oval shaped intake port. hence why you really can't slap a 4v intake on 2v heads.
as well the 4v is not as wide,this is caused by the width of the 4v head in comparison to the 2v heads.If someone would get on the ball and make adapters it may solve alot of 2v intake issues.