Hey Guys,
First post. :) First of all i would like to thank everyone for their valuable advice and input that is shared on this forum. It is great to see so many other proud stivo owners representing the big T even though we do not have the support from TRD, Toyota etc and the majority of the time the help that is required in modifying our cars.
FYI below-
Exhaust System
The 2.4 litre Altise utilises a variable back pressure muffler. At low speeds the variable valve is closed, forcing the exhausts gas to flow through minute holes, thereby increasing the 'expansion ratio', resulting in reduced exhaust noise. At high engine speeds the variable valve opens allowing the exhaust gases to flow straight, thereby reducing back pressure, which results in an increase in engine power.
I assume that this is the same design as our mufflers.