Riser Exhaust 3.5" PCM H.O. Ford - GM OEM | PCM R029011 3 1/2 in. Exhaust Elbow | Pleasurecraft R029011 OEM Pleasurecraft Marine HO Exhaust Elbow Riser 3.5" Riser 3.5" PCM Exhaust Elbow fits 5.7L Engines - R029011 Fits Ford engines and GM 305/350. Its outlet is 3.5" The 3.5 inch exhaust is used on High Output (HO) engines such as all GT-40 engines and engines labeled High Output (HO) from 1991 and up. Please verify if you have a 3″ or a 3.5 inch exhaust. Note: the manifolds are the same for either size riser. The 3.0 inch riser is Item# R029001 and is generally used on PCM manifolds prior to 1991