Ok, well this is my opinion, bear in mind I have a plenum and HF cats too, but when I installed the pop charger, I noticed the roar first of all, you really can hear it sucling the air in. The heat shield seems quite effective and in my opinion no less effective than the other heat shields. Heat soak, not sure, but I was sure when I installed it it felt more torquey. I won't really know until I get the ECU sorted, but you can feel it pulling more and it certainly sounds the part