Are you building a custom exhaust?  These Exhaust flanges will help simplify the process.  Compatible with GS, KZ and Hayabusa cylinder heads.  Accommodates 1 5/8 (1.625) O.D. tube. Sold as set of 4.  Can be made for 1 3/4 (1.750) O.D. tube as well.  Please contact us for custom sizes.