I have a JJR kit on mine. The piping sucks and didn't fit properly, and the kit does require a lot of cutting to fit. I ended up having to get half the piping custom made. You'd be better off shelling out a bit more for a better brand that fits properly first time, every time. I wish I had, would've ended up costing less.
The core itself seems fine, I haven't had any issues with it. That said, I'm still only running standard boost.