^The dealer.

^ amazon

fyi! spray a small mist of water into a hot engine while running, intermittently, this will boil on contact, and blow off the carbon at a molecular level. cleans everything in the combustion chamber! piston heads, valve faces, valve seats, stems, anything thats hot and carboned! about a cup through a spray bottle should do. it will blast right off the surface. bad side of things! then you got carbon down in the catalytic. not good!
as i compare seafoam to a h2o blast:
seafoam will dissolve the carbon. unburnt gases travel into the cat and gunk up things. also the seafoam saturation will ruin all the o2 sensors. o2s can not be washed or saturated buy gas or cleaners.
water kinda knocks off the carbon as a solid or flake. water has no effect on the o2 or the cat. the carbon may accumulate either way and clog the cat. i have not ruined o2s buy using the water trick!
worth a shot if its free

also the "death flash" or dealer revision sticker is to reduce the timing on a heavy acceleration. this will lesson the pre-det. in no way will a death flash increase the pre-detonation condition. a tuner chip just may make it worse. either your running too lean or the plugs are too hot. do you have platinums in it? how old are the o2 sensors?

The Seafoam specifically states it 02 and cat safe, and it has to be, by law IIRC.

I've Seafoamed mine, and have had no issues. The only issue I've had is the massive increase in manly performance.