I would think that the warranty carrier would have to show the failure or issue was a direct result of any upgrade done to the bike. Just thinking out loud.
I have recently started looking at them too since as you said the cat is bad news. Will putting new headers, stage 1 and a fueler hurt my warranty? Thx
Technically, the dealer can void your warranty if you remove the cats, bypass the O2 sensors, add an aftermarket fueler, add slip ons that are not Screaming Eagle, or even add a trailer hitch. Notice I said "technically". Its up to each dealer to decide. Yes, they would have to prove that your mods is what caused the problem in the first place, but in the mean time, your bike is down and you're going to have a huge hassle on your hands, if the dealer wants to be a butt head about the whole thing.
Man, you just don't know which way to turn. Have only done slip ons...no not screaming eagles and nothing else at this point. Was mainly wanting
to reduce the right side heat some. This 2014 is hotter than my 06 SG I do believe. It is unlikely I would go to the dealer I purchased from, others are closer. Hate to pay the dealer for stage one changes or putting a new header on, (warranty) when it can be done so easily and much cheaper on your own.
This might help when talking to the dealer about what you can do to your bike: FTC Validates Right to Install Aftermarket Parts | Specialty Equipment Market Association