Ok I did quite a bit of research into the exhaust system for my 04 cobra. Just to let you know I do have some experience with metal, I have been a machinist for TRW in the space and defense sector for 23 years. Now we are know as Northrop Grumman(.
As I looked through the systems the main thing I looked for was durability. I didn’t want some nasty rusted out system messing up my nice stang in just a couple years. The material of choice is 304 stainless. As I looked at systems I noticed things that were not good.
These quotes are from the web sites of the company’s.
Bassani:
"'COMPOSITE' steel for durability and backed by a LIMITED WARRANTY"
(This is a combination of mild steel or aluminum. Mild steel rusts very fast and aluminum corrodes and goes away very fast, especially in areas that use salt on their roads.)
"Precision-engineered stainless steel for durability"
(what kind of stainless? 300, 400 series? Not all stainless is the same and once again 304 is the best choice for corrosion resistance and strength)
"durable STAINLESS STEEL internal construction housed in a 16 gauge aluminized steel case"
( nice that its stainless inside but outside will rust once the Alu. is gone)
Flowmaster:
“3.00" Stainless Steel Tips”
(well the tips might not rust, depending on the type of stainless)
“Heavy duty, thick walled (.075) aluminized pipes”
(Thin and guess what… Rust)
MAC Performance:
“Stainless Steel Tips!!! True Fit design (ball and socket fitting) eliminates the need for gaskets, muffler clamps and welding. The system is made from 16ga aluminized tubing.”
(well the tips might not rust, depending on the type of stainless)
SLP Loudmouth Exhaust:
“SLP latest additions to the exhaust world are 100% stainless steel.”
(What kind of stainless?)
Borla:
Borla exhaust is built of aircraft-quality T-304 stainless steel -- stainless inside and out, not mild steel, not aluminum, not coated aluminum, not just wrapped with stainless on the outside for show. Coating techniques, such as aluminizing, can somewhat prolong the life of mild steel, but coatings suffer at the weld points. And, comparing aluminized steel to T-304 stainless steel is like comparing gold-plated metal to solid gold! T-304 stainless steel has the highest chromium content, making it the most resistant to corrosion and therefore the most desirable material for a long-lasting exhaust system.
I know a lot of people are after the sound of a system. I personally am after performance not show. Durability is a huge part of performance.