This is just some ramble I thought of & had nothing better to figure out, this information is all done by me, so I know some of it might be wrong I am no math major. Use this information in any way you want, just dont blaim me for any problems you have with it.

American Standards:

Stock Pipe:
Pipe Size = 1.75"
Pipe Surface Area = 2.4"

Pipe 2:
Pipe Size = 2"
Pipe Surface Area = 3.14"

Pipe 3:
Pipe 3 Size = 2.25"
Pipe 3 Surface Area = 3.97"
------------------------------
Stock Pipe vs Pipe 2:
Increase in Diameter = .25"
% of Increase = 14.28%
Increase in SA = .74"
% of Increase = 30.83%

Stock Pipe vs Pipe 3:
Increase in Diamete = .5"
% of Increase = 28.57%
Increase in SA = 1.57"
% of Increase = 65.5%

Metric Standards*:

Stock Pipe:
Pipe Size = 45mm
Pipe Surface Area = 1590mm

Pipe 2:
Pipe Size = 50mm
Pipe Surface Area = 1963mm

Pipe 3:
Pipe Size = 55mm
Pipe Surface Area = 2375mm
---------------------------
Stock Pipe vs Pipe 2:
Increase in Diameter = 5mm
% of Increase = 11.1%
Increase in SA = 373mm
% of Increase = 23.5%

Stock Pipe vs Pipe 3:
Increase in Diameter = 10mm
% of Increase = 22.2%
Increase in SA = 785mm
% of Increase = 49.4%

* All the metric numbers are rounded for more simple math. Also The pipe 2 & pipe 3 size are different then the american standards, I did this to show if using mm to measure your exhaust & have pipes made in that size, its much easier to figure out.

Im sorry if information like this has been posted before. The infomation could be used for basics in helping you decide what size exhaust you want. It also shows how that just by increasing from 1.75" pipe to 2.25" pipe is a big difference, might make some people think about a full cat back in the 2" pipe size. This information is also just the pipe, when figureing exhaust flow one needs to know a lot more then just this information.

 

i added this to the tech section. great info.

 

Nice post. I like it. Thanks for sharing these information. Keep it up.