g-man
SILVER Star
The riser being the center of the exhaust manifold where air "rises" to come up to the heater control valve and lets hot air up to the bottom fo the intake. Basically the flat sections where the intake and exhaust are bolted together. Once separated the intake can be put on a flat surface but the exhaust manifold is countoured in a way that prevents the flat area from laying flat on a surfaceI think I may not have actually answered your question. The riser at the front end of the exhaust pipe?