Use these larger bore flanges for the 2.50" exhaust pipe size. These flanges are not overszed units that our competitors sell. Oversized flanges will cause clearance problems with starters, etc. These are the strongest fittings in the market. Some of our competitors provide easy -to-break aluminum flanges in the name of "cost reduction". Photo #1and #2 are bare castings, photo's #3 and #4 have the Gray Ceramic Coating.
This flange is required for the over sized collector for the D-Port headers for 64-67 GTO, can be used on 2.20" stock collector if using 2.50' exhaust pipe 64-67 GTO, one 3-bolt flange is required on the round port over sized header right hand side on the 64-67 GTO