I've just got a Haywood Scott de catted down and Centre pipe which I'll be leaving next month. At the moment I have a unknown back box on there that came with the car, from investigation, it may be toyosport but there has no sign of this on the box. All I can say is that it's 3 inch tail pipe. I also have a back box from a STI.
What are the chances of either of these going well with the de cat pipes and what sort of issues could I face?

 

Post a picture if you can that will help.