?? Advance intake cam 5%??

[E30 Luck]

So i found a page on bolt on mods to bring the M42 to life more... They say its alittle detuned from the factory and you can advance the intake cam 5% to get more power out of it.. Does anyone no more on how to do this??? They say the M42 has ajustable cam gears Stock!!

http://bmwnut.blogspot.com/2006/04/1991-e30-bmw-318is-performance-mods.html