Stop in for a cup of coffee

WV64Signet said
Swinger Sprinkler?

it has a purpoise

memike said
If you guys are talking V8 or /6 I can tell you Charlie here told me this, all engines need back pressure, when I had my 73 Challenger 340 car I had unbolted my collectors and tighed up my exhaust to get a time on my car, plus the cool factor of open headers at George Rays drag strip.
Open headers ran 8.69 to 8.90. Then I hooked my exhaust back up and it ran 8.10 to 8.20.
Charlie advised me to run my two 1 1/2 " drop pipes off my /6 to a 2.1/4" single pipe.

Glad I did, no drone at all and a bunch more power at 2800 rpm threw 5000 ram

Calvin Elston was often pushing guys to size down. He had a rule of thumb posted on his blog (now gone). Instead of thinking about pressures, focus on velocity and flow. The most important goal is to keep the exhaust gasses moving away from the exhaust port.

So Charlie was right, but the description might be confusing. When the header's collector flange is open to atmosphere, that 14.7 psi trying to push up into the header.