Wrong- it's a GT Concepts manifold once marketed by Texas Rebuild / Turbochargers.com and discontinued around 2007/2008.
If it were an old SBR manifold it would have had the raised webbing on the top, and it also would have cracked in half by now.
The GT manifolds were cast from a ported MHI Evo III manifold, so it's like buying one that has already been ported. The thing I didn't really care for is they ported the divider off the manifold they used as a mold, so there's nothing to divide the cylinder pulses like there is on the factory manifolds. This has been proven to slow spool time down a bit.