Thermo-Tec were one of the originators of exhaust wrap - around 25 years ago. This is one of their most popular products.
 
Wrapping exhaust manifolds with insulating wrap maintains hotter exhaust gases, allowing them to exit the system faster due to their decreased density. This increases exhaust scavenging, along with lower intake temperatures.

Be aware of cheaper alternatives - Thermo-Tec exhaust insulating wrap will not over-insulate a system when properly installed due to a proprietary coating. Thermal Conduction Technology (TCT), developed by Thermo-tec, conducts heat across the wrap's surface. This unique coating controls heat build-up and dissipation. 
 
This exhaust wrap withstands continuous heat up to 1000°C and contains no asbestos.
 
Measuring 2" (inches) wide and 50' (feet) long, this pack is generally suitable for a 4-cylinder exhaust manifold.
 
Other sizes are available on request - we have only listed the most popular size to keep things simple.  Also available are the metal tie-wraps for securing your wrap, and Hi-Heat coating to protect your finished wrap from liquid spills and abrasions.