Q: I let my uncle change my pads and rotors and now everytime i press the brake all i get is an air sound scared to drive

Usually a hissing noise when you hit the brakes involves the vacuum brake booster. But it seems unlikely that working on the brakes should effect this component. Changing brake pads and rotors is a pretty straightforward job, even on a Cayanne. So I find it hard to imagine that your uncle did anything that would make the car unsafe, but then again, I’ve seen some pretty outrageous things over the years so it’s hard to say for sure from this chair. Probably the most common mistake that home mechanics make is not correctly installing all of the hardware, or leaving it off altogether. Sometimes I see the wires for the brake pad wear sensors incorrectly routed, so they get involved with some moving part. More seriously, I’ve encountered brake hoses that were twisted when re-installing the caliper, or caliper retaining bolts that were cross-threaded or not correctly torqued. So in the interest of safety, I suggest you Contact Your mechanic to have a technician come to your home and inspect the brakes on your Porsche to make sure everything is correct. Your Uncle doesn’t even need to know.