To be honest, ran it in the Summer of 2015 a few times at track and Woodward and drove it around town in Detroit and back here in New York a good amount of times in hot steamy weather and so far so good.

I only drove it last Summer 2016 a few times around the streets (one trip was an hour or so out to Long Island in traffic) because I've been busy with work and could not put in the amount of usual miles that I would apply to such a car.
I go under every so often and it looks like the day I installed it.

A few things to consider.
My system is of course from the collectors back where the heat has already come down a few hundred degrees from the primaries, but it was the aluminum mufflers that cut weight the most. No vibrations is the key and using 6061 grade with good penetrable tig welded joints.
The tubes can be had at any good well stocked and knowledgeable speed shop. S&K Speed out here on Long Island has every size tube of aluminum available in stock and it should be common in other outlets being that most Turbo applications keep up their demand.

I also ran a thin wall 321 military grade stainless system along with stock Dynomax Ultra-Flow muffs for a good amount of years and cut off a good sizable amount of weight there.
I forgets the gauge wall though, but they were wafer thin and I got them from Burns Stainless out in Costa Mesa, Ca.

The Aluminum system of course was the lightest and the muffs were done by a cat in Canada by the name of Chris McQuay at Unobtainable welding who made them to my exact Ultra-flow $pecs for me.

I'll look over my notes and post the weight differences compared to stock steel exhaust.
Here's a mock up of the system before the muffs.