For those of you that fab your own pipes. How does one go about figuring out how to calculate for back pressure? Is there even a calculation or is it hit or miss? Do you build them, bolt them on and see what happens and baffle them from there?
The reason I ask is I have a friend that wants to fab his own pipes but this is his only hesitation.
Thanks,
John

 

There is a dedicated formula that may help.
I'll dig it up and post.
Scott

 

Cool!

 

back pressure isn't a calculated thing..stock the bike has baffles that restrict the exhaust flow,it is tuned to run that way..pull the baffles,it runs differant.you will only notice it on a dyno..or if you are racing and that extra tenth of a second matters.the only problem you run into is stock bikes are way too lean to meet epa standards,horrible on the engine but looks good on paper.when the engine is freer flowing you get more air/same choked fuel = detonation. richen up the fuel mixture and run anything you want to