B18c1 block with a b16 pr3-4 head. It also has a p73 itr intake manifold with a 98spec 4-1 itr header. To a hks test pipe, factory res and spoon n1 axle back. Still makes enough back pressure, didnt really lose low/ mid range torque as much. But my made alot of top end horsepower. I hope u guys are looking into spoon exhausts! They sound great!