Insulating Wraps By High Output
Generally, any of the insulating wraps will raise the temp inside the pipe and thus speed up the wave activity inside as well. This will cause the wave activity to be efficient at a higher rpm than before and raises the powerband (usually narrows it a tad, too). If it is jetted and timed complimentarily, there is usually an increase in power at the new, somewhat higher peak rpm. Depending on how far down the pipe it is wrapped, there is often a corresponding loss of low speed power. You see this trick on drag racing vehicles quite frequently because they are trying to build up heat in the pipe quickly to match the high rpm that they will be finishing their race up with in just seconds. (The other big deal with header wrap for the car guys is that any reduction in underhood temp means a cooler and thus denser intake mixture.) If it is done correctly, in these situations it can be used as a sort of pre-timed, variable exhaust system. But because too much heat wrap can cause temps to go too high in extended use situations, you should be very sparing with heat wrap until you have verified it to be safe for your length of time of operation. Expect to need more main jet and quite likely more mid range fuel as well. You may have to limit ignition lead a bit, too. Good luck.