I think I misunderstood you because I thought you said before if somebody is to add exhaust,air intake, and your Xcal2 the injectors are still ok but that is all you can do before injector upgrade? The way I understood you since I allready have air intake, Xcal, and want to swap from Flowmaster to magnaflow I would also have to do an injector upgrade, is this true?
I had a long day I may have understood you wrong. Thanks
Anybody else?
2002 5.4

 

You'd be fine. All you are talking about is switching mufflers, which would still leave you with what is considered the "Stage 1" kit (intake, tune, exhaust). BTW I have a flowmaster exhaust and will be doing the same thing coming soon, I'm just keeping the existing pipes and putting in the magnaflow muffler (Mike has said it is fine to do).

There is at some level of HP (and you'd have to search for it depending on year/engine etc, I think it's as you start getting into the stage 2 kits) that you'll need to replace injectors, but with those 3 items you are fine.