JB 1 TIME

I purchased & installed a Flowmaster Cat Back Outlaw Series exhaust for my 2016 5.0L in October 2016. The picture below was taken in May 2017. So much for 409S stainless steel. It should not look like this after just one mild winter in Cleveland, OH. Should I call flowmaster and see if they'll replace?

GMC to Ford

409 stainless steel is pretty low quality although popular in exhaust systems due to low cost. The minimum requirement for SS is >10.5% Chromium and guess what the minimum specification for 409 SS is 10.5%. Based upon blowing up your picture, the brownish shiny coating is a protective oxide layer. The remainder appears to be chloride pitting corrosion. I suspect your truck was exposed to road salt this winter based upon the looks.

Even Weber grills have gone the cheap Chinese junk route. They were previously made in Palatine, IL and used 304 SS. The new models use 409 SS made in China.

SixShooter14

I recommend anyone above the Mason-Dixon or within 50 miles of a coast to go with 304.

JB 1 TIME

This is after one mild winter though. I just can't believe the stainless steel they use is THAT bad, even if it is the cheapo stuff.

acdii

Wow, the exhaust on our 95 Grand Marquis doesn't look that bad, and it has been driven in Northern IL winters for a long time.

MetalCutter

400 series stainless is magnetic and will rust. 300 series is non-magnetic and won't rust.

JB 1 TIME

Think I can get flowmaster to do anything about it? If not I will be junking this and putting on a borla.

speeddemon0712

The only way to find out is to give them a call and see.

WXman

In my opinion, that's 100% normal and even my factory piping looks like that. It doesn't affect the tubing structurally at all. Going to take many many years before that fails.

JB 1 TIME

Normal after one LIGHT winter? The roads weren't salted more than a handful of times this past winter. And it looks like garbage now.