It probably took me 4 hours to do it . . . but I'd never done it before and was pretty slow. I also did it without draining coolant, which in retrospect would have made the passenger side head a lot faster/easier.
The Injector Dynamics injectors for the SG models require either modification of the stock wiring or the use of ID's pre-fabricated adapters. The adapters cost about $45 for the set and make the injectors plug-n-play, so they should not increase the shop's labor hours, but would increase the total charge if the shop has to supply the adapters. If the shop chooses instead to modify the stock connectors it could well run about an hour of labor.
What rugbugboy said and thanks for the info. He's throwing in the adapters ($50 which is a half hour of labor) so that puts the job's actually time at 2.5 hours. I can sleep at night with that situation.