This manifold will give you looks and performance never before available in cast iron. Provides a tight-fit for steering and clearance issues and flows better than original Corvette manifolds. Manifold gives the same performance as tube headers with classic ram horn styling. 2-1/2" collector uses standard reducers or tight tube extensions. Includes gaskets and bolts shown in the picture. Note: The port size is square and large enough for most round port heads. It measures about 1-1/4" and should be sufficient for most small block cylinder heads. Will clear most straight and angle plug heads. Will not clear original-location steering boxes in 1935-1940 Fords or 1955-1957 Chevy cars. Will not work with GM "fastburn" heads. These fit great in a variety of street rod and vintage truck applications (particularly those with Mustang II-type suspensions). This is a high quality set of ram horn headers.