Hi all wondering if you could help me out with a question i have regarding the installation of a balance pipe in an exhaust system......

At the moment i have a dual exhaust installed on my car and wish to install a balance pipe. Due to space limitations i have decided to go with the 'H' type which leads to my questions...
Is the balance tube required to be the same size as the exhaust system or can it be smaller? and is there an optimum posistion (measurement) before the mufflers?

Thank you in advance for the help!

ps any links that may help greatly appreciated