Here's the final math.
If this were to have been a full aluminized steel exhaust stretching out to the rear bumper with tail pipes and all, it would have been conservatively weighing closer to 88-95 lbs installed, so in this case and in theory, 45 to 55 lbs would have been discarded by going aluminum. Basically a 51% weight drop.
With this project first being a steel midway system at 58 Lbs, in actuality, 36 lbs were discarded when going aluminum. Basically a 62% weight drop.
But WEIGHT! there's more.
Measuring at 3-1/2" then reducing to 3" as a midway, I can just imagine what the final weight would have been if it was a typically sized 3" pipe system reducing down to 2-1/2" as a midway. Probably just under 17 Lbs.
It must be stressed that the ability for headers to rid heat more efficiently than factory iron exhaust manifolds is a determining factor behind this. Temperatures vary from car to car, but the temps at a factory manifold flange where it meets the pipes could be much higher than a header collector where it meets the pipes. This is usually because the factory iron exhaust manifolds are shorter and closer to the engine exhaust ports where exhaust flame temperatures are obviously higher and more intense. It could be assumed that high heat tubings such as 321 stainless could work with an iron manifold to help transition exhausts to cooler climates further down pipe, but again it all has to be tested and verified to factor which material-either steel, stainless or aluminum- could-would-should make the cut. Exhaust noise is a whole other field.
The temps on these particular collectors were not high enough to make aluminum soup and the lighter alloy was supposedly able to tone down the exhaust note, so it got drafted in.
The benefits on this project were cooler pipe temps, no rust nor oxidation issues and surprisingly a quieter exhaust note.
It had to be tucked tight and high with snugged clamping to not allow vibration which is any hanging systems nemesis, especially aluminum.
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