Nick here's some links to help you. I don't recommend going to Acura to buy the inj's, here's one online source.
HONDA PARTS UNLIMITED... YOUR SOURCE FOR OEM HONDA AND ACURA PARTS AND ACCESSORIES!!!
RDX Injector Info - onecamonly.com thats probally one of the best write-ups I have ever read. You don't have to mod the inj's or the manifold, only need to change the clips.