The 'B' word

[semper_rideo]

That's back-pressure.

I've been looking into exhaust mods for power. I've read a lot on a lot of different forums. It seems there are people everywhere who eschew education in favor of rumors and sophistry. For those who like science I have these links:
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm

http://www.thrashercharged.com/tech_htm/exhaust.shtm

http://www.thumpertalk.com/forum/showthread.php?t=659727

http://www.aa1car.com/library/exhaust_backpressure.htm

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

And for those who don't like science or just don't have time/patience to read:
Back pressure is bad. People who say "you need back pressure" have been misled. They really mean: you can live with a minimal amount of back pressure IF exhaust velocity is optimized.

 

[ridenby]

Run a glass pack myself,sounds good bumping the rev limiter.

 

[iamweasel]

Some interesting stuff there. I stumbled on a similar article while researching an exhaust for my KJ:
http://viperperformance.co.za/index.php?option=com_content&task=view&id=22&Itemid=35
It also refers to the natural frequency of exhaust pulses in a particular engine.

It's a bit of a long read, but the conclusion was that using a narrower header for certain cylinders had a significant increase in power.