two turbos.
Actually it's been done - but the one's I've seen had the other turbo kind-of up on top of the motor - assuming needing some kind of custom hood arangment. Also - you better get you're heads fireringed before you even think about twins - your headgaskets will NOT be happy with you!! And you'd need to add a BUNCH of fuel (SERIOUS injectors)to need all that boost and actually do anything with it, and then to drive those big injectors you'd probably need to upgrade the HPOP with one of the new dual setups that are coming out now. Man - I could keep going - the list goes on...................How hard? NOT at all easy or cheap!! NOT saying it can't be done - but it's a tad bit harder than slapping another stock turbo in-line with yours!!
LOL. 70psi 2000 EGT is what he says when pulling the sled.
http://www.4andersn.com/projectpics.html










