i have seen this many of times and had alot of debates about failflow exhausts. i have seen them sh1t the baffles out into a heap, fall off cars, rust to bits in a few months. im not getting into the debate, instead i am going to post some pictures of a power flow exhaust that came on my 182 when i bought it in April and you can judge for your self;
as you can see, the system is poorly constructed and has started rusting. i have found the original receipt and this system was a matter of months old. the problem with power flow is the bottlenecks they have from bending the tube and that all the welds are MIG instead of TIG. so although the tube is 304 stainless, the welds are just ferrous metal which will oxidise and corrode. ans before anyone says it, all power flow's use MIG so all power flows corrode at the welds.