Scooterotica

A well written and comprehensible insight to 2t tuning.
I found this because I was looking up assertions that the tailpipe of an expansion chamber can be at least partially inside the chamber itself. Apparently it can within reason, and with no loss of power.
The outlet does not need to be at the convergent end either, but then you all knew that anyway.

If you have the tail pipe starting in the Center section ie the largest Dia of the exhaust pipe, this is where the gas pressure is at it's lowest! If you fit the tale pipe at the end of the rear cone it is at the highest pressure point. By using the tail pipe start point in the Center section it also lowers the db level of the exhaust before entering the muffler unit. This is why our Taffspeed exhaust systems are quieter than most! Also by using a 0.55% to 0.65% of front pipe Dia you end up with 22mm to 26mm bore size for your tailpipe. Using the larger Dia will keep the engine temp lower when at full throttle.