Hi Bob
Not necesar remove, in winter must cover 1/4 - 1/2 part of cooler (not over the funnel).
Cooler preheat the air and funnel add pressure and air folw through the mufflertube. What in important, in cabin close air folw straight out for example with yoke cover. http://www.aerokits.net.au/Savannah%20Tip%20No%2024.pdf
Hi Dr Zoos
Not plastic ducting, SCAT ducting temperature ranga to 550 °F ~ 288 °C, not problem connecting to muffler.
Osteri