carbureted 5.7 - 6.1

yeah...heard that about the XV intake. the MP item is just too darn pricey for my wallet. are you running a single or two fours on the modman. my bonnet has a power bulge directly above the carb, so should be all good.
on the headers side of things i see indy do flange plates in 1 3/4" for the 5.7 and 1 7/8" for the 6.1. would it hurt to use the 6.1 on the 5.7. i'm thinking that the slightly bigger size at the port exit it will scavange a bit and help flow.