my 7 didn't pass emissions, and they said there was an exhaust leak. Where are the most common places to find holes in the system? Would it be better to wrap it with that steel tape **** or to just replace the offending pipes?

 

Could be anywhere. The whole system is probably pretty rusted. Better to just replace what needs replacing

 

There is no steel tape, it's aluminum. Good chance that the heat from the exhaust will melt the adhesive, then it will curl up and deteriorate from there. Do You need to pass emissions or just pass a visual inspection? If it's visual only, you could go with headers and a custom exhaust or the complete Racing Beat system.