There isnt a mopar manifold available.
Basically the only performance parts available from mopar for the caliber are:
Sway bars (unkown maker),
intake (made by AEM),
Coil-overs (made by KW),
Strut brace (made by DC),
and The stage one ECU (programmed by flight systems).
To answer your question:
Realtune offers a ported mopar manifold.
Steedspeed offers an aftermarket manifold.
AGP turbo is developing a cylinder paired manifold (which will be pure awesomeness)
Our manifold does not have a cat on it or anything- it just goes straight to the turbo. From the turbo the exhaust has a pre-cat, also known as the "o2 housing", then a cat. The pre cat is a huge restriction as its a 90* bend right off the turbo. Several small aftermarket vendors have replacement downpipes to help this.
Hope this helped?