Saturn S series Twin Cam cylinder head had now featured a new roller-rocker setup with hydraulic tappets and roller cams replacing the conventional bucket lifter setup of the previous engine in the S series. Also introduced for the 1999 model year S-series vehicles that were sold in California was a different type of an exhaust manifold that housed an upstream catalytic converter (this converter had heated up much faster than the conventional unit, and it had also decreased exhaust emissions faster as well), and it also had provisions for an air-injection reaction system (This had injected fresh air into the exhaust to reduce
Exhaust heat management performance and avoid burns from motorcycle exhausts. Heat wrap consists of a high-temperature synthetic fabric which is wrapped around the manifold. Often sold as a cheap and easy way to boost horsepower, exhaust wrap does not increase engine output much. It can decrease engine bay temperatures and increase exhaust velocity. Lower intake air temperature — and therefore increased air density — may result in an increase in engine efficiency and power. Hotter exhaust gases travel faster which may reduce turbo lag and improve exhaust gas scavenging. There has been much debate if heat wrap is better than plasma-sprayed coatings. The