i can't believe no one has come in here and actually called this mani by it's proper name. That my friends is a MAM Thumper manifold the same one that was used in the 30r big boy kit's. T3 flanged w/ an external gate. How long have you had it?
This manifold has bigger primaries, a t3 flange, and a external wastegate port. The MAM bullhorn had smaller primaries and only a t2 flange. This was their flagship manifold for making big power. Cwill made over 400whp on this manifold.