Exhaust pipe material vs velocity

[Jason Garrett Young]

> > Question- Would using a more heat resistant material to keep the
> > heat in and thus the velocity up, allow a person to run
> > a slightly larger diameter exhaust without low end loss?

Your logic seems to be on tap.  Steven's idea of wrapping the pipes works
well, also.
There was some web page that showed by simply wrapping the headers, there
was a gain in HP.  Of course this could be because the radiant heat from the
header was diminished  (what was propelled to the motor).

I've noticed several racer's wrapping there side draft exhausts.  I would
assume this is for power and not for esthetics and/or safety.