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.