What was it making at the wheels?
IMO your car is not mapped. The full turbo back exhaust will allow more air flow and is less restrictive. Accompanied by the intake you will see an increase in BHP.
Now, to get the most of the mods and the car you need to map the car. However, you will see misfires and possible coil pack failures so you will have to buy a high pressure fuel pump (HPFP) and have the car mapped to suit.
After that, you could then install the RS4 fuel valve reg to help fuel flow.
Personally, I would sell the dbilas and get a AMD/ITG/REVO intake as they have come on a lot since 2007 when the dbilas was first released.