Factory Exhaust Manifolds are 1 3/4 primary?

[r25558]

I was told by Roe Racing that the factory Exhaust Manifolds feature 1 3/4 primaries from the factory? Can anyone else confirm this?

If so, I'm just going to install a 3" catless Midpipe in addition to the existing Corsa Cat-back and call it good...

Thanks in advance!