Thanks for the replies, but my pipe is 27mm all the way to the back edge, stock is about 23.4mm, I will need a 27mm I.d. gasket , as a tempory solution, I machined an aluminum sleeve 27.2 mm I.d. by 31.2 mm o.d. by 31 mm long, and sealed with high temp rtv, surely, Mitani must have made something to be able to mount their pipe to a stock midpipe. Thanks, Ken