Leaderboard

I checked with my engineer and passivation and polishing/wire brushing are not the same net effect with 304 stainless steel. 304 stainless steel is more than 50% iron, around 20% chromium and about 10% nickel. Passivation dissolves the iron on the surface leaving the chromium, nickel, and other trace elements on the surface. These metals left on the surface oxidize when air dried after the acid treatment and form the protective oxide layer that prevents the iron underneath from oxidizing (rust). Polishing/wire brushing exposes fresh top surface of metal; in 304 stainless steel this is more than 50% iron so when the oxides form it doesn't make a protective barrier because of all the iron on the surface. It was explained to me that is why we passivate the equipment in the food processing plants after polishing them. @Ducnut, your headers look awesome and I congratulate you on getting them to a show bike finish. 304 stainless has corrosion resistance but this resistance decreases as temperatures rise, which unfortunately exhaust pipes get hot. Also, 304 stainless will corrode when exposed to chlorides at higher temps. Most of us ride in nice weather so it may not be an issue at all. If I can offer some friendly feedback, keep them clean, dry, and away from road salt (sodium chloride) to keep them looking great and avoid potential corrosion at the welds... or passivate them before installing. Your bike, your call. Have fun and be safe!

That beautiful machine looks quite lonely. But at lease it is not lonely from being in the garage all the time.

I ordered one from a supplier and it indeed was the "big mouth" version. The K&N that came with the bike was the older one with less area. Still good but I wanted max air flow. So, I just ended up selling. I'm thinking any supplier should have the updated version unless by chance they still have old stock (NOS). So, get one from one of the bigger places, assuming they are moving inventory more than the smaller distributors. Just my 2 cents.

IIRC, if you order direct from K&N, you’ll get the larger filter element. I speculate the smaller element is an older-style filter that some distributors may have had leftover.