cleaning them is cheap and easy, you might aswell do it before putting them in. coventry's sell injector repair kits, which consist of seals, pintle caps, etc, and a sonic bath can't be worth that much, i've never paid for one (the benefits of working for a dealership) but call your local workshop, dealer, whoever and ask them if they have an injector bath.

they plug your injectors into a sonic bath which cleans out your injectors, they can flow test them on the same machine i'm pretty sure.
and if you buy the new o-rings, seals, baskets (filters) and caps as a kit from covs for under $10 a pack (does 2 injectors) you're good to go.