not really...why...because their HYPE is for the most part just that..unless your doing some kind of racing(like that FAST racing) your not really gonna notice the MAYBE 5-10 MAX(if that) HP advantage that the 340 hi-pos have over other manifolds like say the stock log style SB manifolds from say 73/74 just pull up that old mopar muscle test they did a few years back..i think on a crate 300 hp motor there was a 2-3 hp difference between the 340 hi-pos and 73 340 log manivolds and ONLY like 5-7 between the hi-pos and 318 manifolds...in otherwords save your $.
