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Magic, Mirrors & Myths

MYTH - All headers make power.  
FACT:  Some engines and engine are more respsonsive to headers than other engines. For example a TR8 reponds better to headers than a Triumph Spitfire or MGB.
FACT: headers can/will make power in different rev ranges. For example , 4 cylinder engine with a 4 into 1 header design will make power at the high rev range. While a tri-Y design (4-2-1) will make power in the mid-range. This is much more useful on a street car since the majority of the drive time is probably in the mid-range.  Another example  of this is the stock cast iron exhaust manifold on 1963 - '74 MGB's. Thsi is a nicely curved runner 2 outlet manifold that goes into a double exhasut pipte that then necksdown toa long single  pip.  We tested some int he early '70's and the stock manifold produced more power through about 4800 rpm than the factory competiton department header.  Once we got over 4800 rpm, the race header started to perform.But, for a hot street car, having power start at 4800 rpm is not necessarily the best option.