TriMill MG MGB Performance Exhaust Header American Made Monza 1.8 NEWNEW Tri MILL MGB Performance Exhaust Header. This is the highest quality MGB header you will look at, at the best price. This is an American made header with a meaty 3 8" laser cut flange. The down tubes are mandrel bent 16 gauge mild steel tubing (most competitors are thinner 18 gauge). Fits MGB (62 74) 75 ON (WEBER). Header comes with gasket and collector. As with all headers, check to see if this allowable in your area. This is a quality made