Which size exhaust housing on my TD06??

[JDMgravy.]

Hey,

As title, im trying to figure out which size exhaust housing is on a TD06L2 20g I recently picked up. Im hoping its 8cm and not 10cm, but im unsure on how to measure the housing??

http://i17.photobucket.com/albums/b85/Rich1275/20121217_104726.jpg

There are markings on the housing but i guess its just casting numbers '49179 - 12300'

Any help would be appreciated, thanks!

[Luvs2slide]

there should be a number on the inside of the exhaust housing...look for either a 6, 8, or 10.