The header is somewhat difficult to install due to the limited space behind the engine, and the catback needs to be welded on. The intake is easy, though.
As for problems, the catback will probably attract lots of cops (very limited sound control). If the header is a name brand, it should be fine and perform fine.
The intake is another story. What brand did she get? Stuff like Weapon R tends to automatically turn on the CEL light.
eBay AEM replicas are fine, along with real AEM intakes. Injens tend to cause excessive bogging on low end pretty often, which can lead to CELs if the bogging gets bad enough.