3" cat back exhaust

I bought a 3" apexi n1 cat back exhaust and now I need the downpipe to fit it all together but I cant find anything that is not a 3" inlet. if i am right I will need to get something smaller cause I have the stock o2 sensor on my 16g turbo. do you guys know of anywere I can get the right downpipe?

The megan downpipe I just got is 2.5 for a couple inches where it bolts to the o2 housing to allow space to get the nuts on the studs.

Subforums....

The Apex'i N1 downpipe bolts to the factory 02 housing.