well if your putting used injectors in its wise to have them cleaned regardless. my FD has rc engineering bored out 550's and new bosch 1600's in it. i won't risk anything with used injectors....

Yeah, old used injectors that have been sitting around for a long time will most likely be bad. That's why you can't really trust injectors from J-spec motors. Old injectors that are still in a running car will rarely go bad.