I've had the burger piggy back tuner, its a great low cost option that is very easy to add and remove. It works well, and gives a decent boost in performance.

There is a free egr mod where you add a resistor to the wiring harness, then you could add some cheap block of plates.

Personally that didn't exist when I setup my car. I'm running a JR stage 2 tune, with EGR disabled and DPF and SCR intact. Have been running this for 2 years with no issues. Car runs fine.