ok i have a 2000 silverado 4x4 5.3 stock with a couple of bolt ons wanted to know if i got bigger injects if it would help and notice a diffrence if soo what size should i get

 

Injectors by themselves won't give you any gains. As you do more mods, such as cam or heads, larger injectors may then be required. You would be able to notice this by observing your injector duty cycle with the proper tuning sofware. The 8.1 injectors (29.9lb = gas, 42lb = Marine) are a direct fit that only require PCM tuning to work.