Remus Exhaust System Purchase - Need Input

I noticed that the Remus does not carry entire cat-back exhaust system, only the muffler (axle back) part. I want the whole thang... what Catalytic converter do you recommend to go with the Remus muffler?? Any one of em? or anything particular. I would like the high flow design though, for best performance. Should I just get any Cat that works with my Infiniti G20 and get the Remus muffler??