[caverman]

I'm confused with your post. Not sure what you're asking about.

I will say that I don't think your "someone in the know" actually knows about the LS3. I can tell you 100% without a doubt that headers and a CAI will NOT require new injectors. All you need to do is surf the V8 sub forum. Every other thread asks about headers and a tune.

An intake does not require a tune but that doesn't mean a tune wouldn't help. Same with headers....it's technically not required but you will have CEL come on and your air/fuel mixture won't be optimized.

You can always go with a set of SOLO or JBA high flow cats instead of headers for now. Those don't require a tune but you'll only get about 20 rwhp vs about 30-35 rwhp with headers.

My best advice is for you to do more research. You probably need to start looking around in the V8 section. These questions get asked constantly.