I just hit my nitrous for my first time and I am having some issues. When it is first activated my O2s drop down very low, and there is audible detonation, then it recovers and still runs alittle lean. How can I fix this, add bigger fuel pills? It is a TNT wet kit running a 100 shot. I have a 255 inline pump and all the mods in my sig.

 

No sig???

Whatever you do...dont spray again till its figured out or atleast think its figured out.
Two likely problems are:
Fuel pump not functioning properely
fuel noid not opening

Do you have a fuel pressure gauge? What does it read when you were spraying?
Test the noids for flow...especially the fuel one.