I would swear I've seen pics of injected Mavs without any bracing at all. I would be interested to know how that's working out... I'm not about to try it myself or suggest it to anyone else, but if someone has already done it I'm curious.
In my two-pennies icon; if you are doing this yourself and are not well versed in EFI electronics, and you are on a budget - stay carbed (you'll still have to change some things to use that engine (enter "search" feature here). If you're not too concerned about budget or time, go EFI. 50/50 (see my gallery for home made braces for EFI app)