Yep, that would be the next step. Which size, type, will depend on your long term goals. But depending on what you're intending to use as a fuel controller can have a bearing on which injectors you should choose.
Personally, if you're looking at any kind of piggy pack system, get the injectors sized adaquatly for your uses, but don't over size for the sake of it. ie. don't get 1000cc injectors if you're running hybrids or a small single, and are planning on using an E-manage.
IMHO, 550's are fine for hybrids, and 650's are OK for T61, T67 etc. (650's for a T67 on very high boost is pushing it though).