I know that by getting a bigger exhaust you are decreasing back pressure and I heard you could have too much backpressure? Could someone explain what backpressure is and how it is important? ;-) Thanks!

-Tom

 

Back pressure is essentially the pressure level in your exhaust system. You can test it by screwing a pressure gauge into the fitting your O2 sensor is in. Anything over about 2.5 lbs is excessive.

Consider, your engine is a pump. If it has to work to get rid of the exhaust gases (high backpressure), it will not operate as efficiently as it could. With low backpressure, the exhaust gases flow nicely out the end of the pipe, and the system works fairly well.

Causes of high backpressure are generally a clogged cat convertor, or simply pipes that are too small for the application. (A one inch exhaust on a V-8 would be woefully inadequate....)

Hope this helps.

 

https://www.thirdgen.org/messgboard/...ML/005393.html

an earlier post of mine that addresses the relevant concepts...