i ordered aan aftermarket header and it has 3 open bungs. i need s13 o2 sensor for the top bung and i need something to fill the other 2. or anybody know where i can buy plugs. i went to advanced, home depot, and ace hardware already, but i cant find a plug that big in such a fine thread. plus its metric so that makes it a little harder......lmmk what you have or what i can do