How is the diameter of a 999 exhaust systems measured?

I received my 999 system today. Its the SIL 50/60 system.

Below are the diameters that I measured. Please excuse the nice photo edit. Paint is all I have on my laptop.

My question is: What are the diameters of the other 54mm and 57mm systems? Like the Termi's, Leo, or Tubi.
Trying to make sense of how these 2-1-2 systems are measured. Is the diameter of the system determined by pre or post collector?
Thanks




Modified by CuStOm at 11:13 PM 2/22/2005

termi systems are measured as tube od, are generally somewhat biased on the high side and are the same size all thru. a 54 usually measures from 52.5 to 54 depending on where you check it.

there's no std measurement procedure - each manufacturer claims the size they feel like i guess.

Found some good information in my quest, thought I would share.
SIL , Akropovic and the new 749R Termi system use the tapered bore philosophy, provides the best power gain without loosing too much bottom end.
Tubi and Termignoni are the same O.D. throughout and rely on the OD of the pipe at the head for their diameter label.
Thanks Mark Sutton and Brad Black for the insight.


Modified by CuStOm at 3:50 AM 2/24/2005

thanks for the post!

Brad
Your statement is incorrect, you should really know better.
Termi systems are measured as the OD of the widest point of the system. A 57mm system for example is 57mm (optimistically over a weld), on the single pipe, on the two into one into two system. The pipes at the exhaust outlet are a different size. The outlet pipes where they join the muffler are the same on 54mm and 57mm systems (around 54mm). The mufflers are interchangeable between the two systems.

Care to share all three measurements? Come on, your bike is a short walk to the garage. Its calling you.....

Both my bikes are at a friends being rebuilt at the moment. I will give him a call and ask him to measure the differences in the front pipe OD's as he has the 54mm Termi on his bike.