Bought a new exhaust and it has an extra bung for an O2 sensor on the down pipe while mine is in the manifold. Been searching high and low for a bolt to plug it. Found exactly that a metric M18x1.5 threaded plug made especially for O2 sensors at www.Sv3Power.com
. $2.95 for part and $8.00 bucks to ship but $10 is cheaper than sending the exhaust back. Now lets see if I can get the place I bought it from to kick back the $10 o me.