The heat from the system is an issue that does require a bit of aluminum heat shielding. Also the exhaust is shielded from the fiberglass cowl. As for the tubing size, it is jumped up to 1/2" after the factory header then downsized at the first exhaust "T", 1/4" if I recall. The troughs for the exhaust dumps are also lines with aluminum flashing, and the exhaust tips are shrouded in aluminum as well. The entire thing is made of copper even the tips which are 90's.
As with all glow engines it makes an oily streak'ed mess on both sides instead of one. The best part is watching it spew dueling smoke trails.