[Miata] - Custom exhaust piping size

[brad boston]

I was thinking about creating a custom exhaust that looks something like
http://tinyurl.com/3afj7w . Since I am not willing to shell out the cash for
something already made, and because I have access to some Triumph straight
through pipes from a Bonneville I got to thinking.  I was wondering how much
smaller the pipe diameter can be after spitting it and not cause too much
back pressure.  I know that splitting the exhaust will inherently give me
come back pressure but if I go from a 2.5 ID pipe (has a cross sectional
area of 4.9 square inches) to two 1.75 ID pipes (combined cross sectional of
4.8 square inches ) it should be about the same... Right?  Since I never got
a chance to take any fluid dynamics courses in school I am a little out of
my element so I was hoping some one with more expertise than myself would
chime in.

Brad
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://list.realbig.com/pipermail/miata/attachments/20070824/d194898b/attachment.html