KTM 790/890 ADV - Norden 901 Shock Heat Shield -2020-2023 Keep the heat out of your 790/890/901 shock with our heat shield! A cooler shock improves your suspension performance and extends service intervals. To meet Euro 5 emissions, KTM mounted a large catalytic converter on the 790/890/901. We're all for lower exhaust emissions but the CAT is located directly under the rear shock. The CAT can be several hundred degrees under normal bike operation and heat from the CAT increases the shock temperature. When the shock oil is overheated, it goes through thermal breakdown. This process changes the oil's viscosity which can lead to increased wear on moving parts and poor suspension performance referred to as heat fade.