If its a good branded make e.g 5zigen,mugen,spoon,J's racing ,for sale on ebay yea ,but if it's a no make ebay job it'll more than likely be garbage imo welds may crack ,bad fit etc
i got a ebay 4-1 its a jap speed. it fits fine and seems to make good top end power when iv raced ek9's. i have an ek4. the only thing i can say is bad about it is im sure 2 of the pipes are longer than the other givin it a funny note like a scooby lol. so at some point i want a 4-2-1 5zigen
I know a few guys on the CSC forum have used their manis and exhausts with no complaints etc.
You usually can get them cheaper on ebay, but I'd prefer to pay the little extra and buy direct from megan