RSM in T.O. has a system for only 1,000.00
You can get a hi flo cat at any speed shop like KVR in the east end. The muffler for a 3.4 Camaro has the single in - dual out we need so you can check the catalogues for different makes like Walker etc. That leaves the pipes. There is a shop that bends and welds in Carleton Place but I never did get a price.
I have a CTC system that has regular steel pipes. You could cut the pipes off the muffler and weld in a hi-po muffler if you want. Yes it will rust out as it is not stainless. It is all 1 piece from cat to tips (no cat no tips)
If you want one made up, you could borrow it so the shop could duplicate the pipes.