eBay headers and cat, yay or nay?

I'm considering buying headers and a high flow cat from eBay for like $80 shipped. Has anyone had any experience with these cheap parts? Are they okay? And please don't tell me to just buy some greddy or skunk2 or any of those other expensive ones. I know they are superior in quality, but I'm not tryin' to spend that kind of cheese. It's either these cheap ones, or keep the original stock. Which would be better?

i have bought a header and cat off ebay and they seem to work perfect. I have never had one problem with either of them.