A major seller of aftermarket cat-back exhausts says this on their advertising:
I'm a bit confused here. Once the exhaust exits the engine, what is it still imparting to the system? (Disregarding a turbo) How does heat 10 feet away in a pipe help the engine perform better? If the EGT at one header is 1,500 degrees, and the second header the same temp, what will the engine care about temp at the tailpipe? Less restriction I can understand. Less temp twelve feet away? Is this marketing hype or should I strap some propane heaters to my tailpipe?Performance Exhaust
Today, choosing performance exhaust can be confusing. A common misconception is that "bigger is better". Many enthusiasts, and manufacturers too, seem to feel that very large diameter pipes are the only way to go for muscle car performance, while we at XXX have found for street use, big pipes just take energy out of the exhaust, both by slowing down exhaust gas velocity and by cooling off the gases. While exhaust may leave the port at 1500 degrees or more, at the tailpipe it’s down to 150 degrees -- a sign energy has been lost. Velocity and uninterrupted flow are the real performance-making factors.