The Exhaust extrator/manifold/header

An exhaust manifold or header collects the exhaust gases from multiple
cylinders into one pipe. Among all of the after market tuning products, exhaust extractors
are on the top of the list amongst the most cost effective power improvement solutions.

Exhaust manifolds are generally and traditionally simple cast iron units which collect
engine exhaust and deliver it to the exhaust pipe. However, when greater performance is
required, this restrictive tube is often replaced with individual extractor which are tuned for low restriction and improved
performance. There are two distinct types of extractors. Four into two then into one (4-2
-1) and four into one (4-1). The different between these two are 4-1 design is mainly
suited to engines that spend most of their lives revving at high RPM in track circuits.
The 4-2-1 design is more suitable for road use, giving a good usable power band across a
wider RPM range.

Tuned Length Extractors
They work exceptionally well in the high rev range and ideal for drag racing.

TRI-Y Design Extractors
The most common design of extractors, Tri-y extractors give you more power in the
rev range that you use on the street. As a general rule you should
anticipate an increase in power, performance and fuel economy of around 10% under normal
driving conditions.