[ls1ac]

Unlike standard cars the exhust is very hot and will melt most rubbers (except HT silicone, expensive) so most shops use a vacuum/blower to pull additional cooling air out the flexible portion of the system. Often a 4 inch steel heater duct with an adjustable 90 on the end will be used before the flexible section. The steel may have a damper on a "Y"or vent holes to let the cooling air in. (This can also be used on a dyno) The flex must be strong enough not to collaps with heat and vacuun.