If your sig is correct then I see no reason why you are pinging with 87 octane. The only performance mod you have is mufflers lol.
It's not the octane, it's your car. :canflag:
K&N Air filters?
Never heard of a warranty being voided for that...
With the couple of mods I have on my car, it's been to the dealership for warranty work plenty of times... just give em' some ****..