Yes, eventually you'll need to get it re-tuned. However, I swapped my tank/pump, installed new 42 lb injectors, and Chicane's pulley and drove my car for a couple days before I was able to get it on the dyno and tune it...BUT, I didn't dare open it up.
It took about 10 pulls on the dyno and 1.5 hours to dial it in to where I wanted it...well worth it!