As it's already been said the factory exhaust is stainless..A low grade stainless probably a 304 type stainless, but stainless nonetheless..
There's no reason to downgrade in quality if the factory used stainless..
Type 304 is not a low grade stainless; type 409 is the lower grade and most likely the grade of stainless used for the exhaust from the factory. See below for why.
My magnaflow muffler is covered in surface rust, which is 409 stainless steel, so...
Originally Posted by guitar maestro
someone got ripped off
"Type 409—cheapest type
; used for automobile exhausts; ferritic (iron/chromium only)."
"... Also, the inferior  grade of stainless is the only cheap material that will last through the factory warranty period."
BORLA uses T-304 series austenitic stainless; the classic 18/8 (18% chromium, 8% nickel) stainless steel.
304 is also non-magnetic due to the higher nickle content; 8 to 10% nickle for type 304 vs only .5% for type 409.
If it sounds like I'm promoting BORLA well ... yea ... I am a fan of theirs.
So the SS on boats is going to corrode.
It all depends on the type of stainless; there are about 30 different types ranging from 100 series to 600 series ...
Also see: https://www.dieselnet.com/tech/diesel_exh_mat.php
There's a good discussion of stainless in automotive exhaust systems at this link.
It's not just salt that will cause corrosion in stainless:
"Also, some commonly used stainless steels, such as type 304, have been found to corrode after exposure to urea decomposition products in high temperature environments." This problem is mostly related to diesel engines.
"Some of the stainless steel car exhaust systems available in the market these days are built of aircraft-quality T-304. It is true stainless inside and out, not aluminum, not mild steel, not coated aluminum, not just enveloped with stainless on the outside for show.
Car exhaust coatings extend the life of mild steel however; coatings suffer at the weld points. Compared to aluminized steel, 100 percent [stainless] steel has the highest chromium content, making it the most resistant to corrosion. Moreover, it is the most reliable material for a long-lasting car exhaust system.
Mods? Yea, I got mods ...
Air silencer delete, warp drive, dilithium crystals, flux capacitor, Slingshot Rubber band power adder, Moonshine & Gas, Leaf Blower Supercharger, Hamster Wheel & Hamster, Energizer Bunny generating 1.21 gigawatts, Mr. Fusion® Home Energy Reactor, hover conversion and a sextant celestial navigation system (The original GPS)
Best 1/4: 1,320 nanoseconds @ 670,616,629.2 miles per hour
"There isn't that much difference anymore between spacecraft, aircraft and modern automobiles..." - Keith Henry, NASA's Langley Research Center
See a list of my real mods and pictures of my car HERE
. The true performance of my car was made possible by the Carolinas Crew Chief, RobertP
at Rob's Tire & Auto