First off, I don't have any personal experience with diesel care/performance, but a lot of people have been burned with sub-par quality.
Your best bet is to have a set of flow-matched remanufactured injectors from someone like Jim Rose at Rosewood diesel
DIY-Injectors.com or Dave Armstrong at Swamps diesel
Swamp's Diesel Performance . You won't get higher quality anywhere and you won't have to worry a bit.
You will need new tunes written for single shots, but you won't be wondering whether or not you did the right thing afterward.
Stage 1s do not have a larger nozzle than stock. The nozzles are stock size but the injector volume is increased for more fuel delivery when needed. These are by far one of the better ways to go with a near-stock truck.