Hello and welcome to the forum,
I have searched hi and low for the exact same thing, all i get is hearsay and stories! Someone even told me he HAS one on LS1tech.com but he wont tell me who makes it,.... hmmmm sounds fishy to me. My mechanic who works almost entirely on ZR1s and ZO6s says he has never heard of one. Good luck and God speed on such a worth quest! Maybe someone will mercifully shed some light on this for us, good topic!
While we are on the subject of stuffing air, check this out... coming soon, this maybe even better than that elusive supercharger.
http://www.turbochargedpower.com/Turbo%20Kits.htm
(Look at the bottom of the page,... yeah thats right they are making a twin turbo kit that is supposed to be relatively inexpensive for the ZR1 coming out this month, hell even if its unvieling postponed it is something to definetly look forward to.
(thats 2 for me Zfactor!
)