Not just another exhaust question, I swear!

[Vichtz]

Ok so I got some serious cash flow from christmas and now I'm lookin to get some HFC. I currently have a stillen CBE so naturally I was reaching for the Stillen cats. However, I found a member on here selling the ARK cats for a bit less and was wondering if they would mate up with my stock headers and Stillen CBE? I looked around for diameters on the stillen pipes which seem to range all over the place from 2 to 2.5, but couldn't find anything particularly useful. The one thread I found divulged into the typical pissing match. Also, ark lists the cats as g37 but I assume they will work for the 370z as well? I know the ARK are 2.5 so if the stock headers and the stillen pipes are 2.5 I should have no issue right? but I can not find the stillen dimensions anywhere. Will this work/fit? Anyone got any ideas? Thanks yall