I just did my DPs (Raceland) a couple weeks ago. I had similar issues with getting the front DP lined up on both the mid pipe and the turbo. I thought it was a fitment issue but it really ended up being me. You need to bolt up both ends and tighten them slowly so everything comes together at once.
The vibration you speak of could be an O2 sensor. They are pretty fragile and one could have possibly gotten messed up when removing or installing it.
2008 E90 TiAg w/ Sport Package
JB4 G5 ISO/BMS OCC/BMS DCI/RL DPs/CP-E CP/Tial BoV/VRSF 7" FMIC/Walbro GSL392/423rwhp & 432tq