Whats the temp of the lid before and after?They do help keep the twin screw cooler by more then you think after the several tests that we have done on our own cars in our group. We also stick on a thermo blanket under the twin screw which helps keep it even cooler again from heat soak off of the engine. Anytime you can isolate the direct contact between metals by adding a material that does not transfer heat well, you will reduce temps substantially. Every bit counts in making more power.