Possibly mark 4? There is a bit of carbon on the inside but it looks pretty much unused to me but I’m no expert. I’m also not sure if it’s been sawn off at the end. Came with some old motorcycle exhausts I bought. Happy to do measurements etc. Has a stamp Mazda PEM 1 on wide section and 3EF05 near the header and a bit further down the header YM439540*15K2433EF05
eBay