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328ftw
In a way the backpressure myth is sort of right, but the pressure is an effect not a cause.
Gas comes out of the exhaust port at x pressure, y speed. If the size of the exhaust pipe is too big, pressure and gas speed decrease. If the size of the pipe is correct, pressure stays the same and velocity is maintained. The pressure of a gas is tied to how big of a hole you are trying to stuff it through. Smaller hole, higher speed, higher pressure. Bigger hole, slower speed, lower pressure.
The pressure is of little consequence, it is a neseccary symptom of the velocity remaining high, but the pressure is ultimately higher in a system with proper exhaust speed, than one that is too slow. So, there is higher pressure in a good exhaust than a bad one that is oversized. But, there is a lower pressure than with one that is too small.
Anyway, you are right in that adding pressure doesn't help, but other people are somewhat right in that maintaining some pressure is good, they just aren't understanding that the pressure itself is incidental, the exhaust velocity is what really matters.
So, back to the main subject, i've heard the exhaust is a big weight pig, so there is another area to reduce weight for sure.
I had a VW scirocco that I removed the US bumpers, which weighed a ton, and put on german bumpers which were very light. Either one is just as safe, its a damage issue. Bumpers do little in serious crashes, but a lot of crunch protection in small ones.
So i guess there is nowhere to get fiberglass engine or trunk lids anymore?
GM
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