If you use a relay, your DRL function will work, but your relay has to be connected to both your Low Beam and DRL leads. (This will turn on your normal beam headlights at all times.)
If you decide to go without a relay harness, you can just forgo the DRLs all together (take out the fuse). You can either run your car without DRLs completely (I do this), or just turn on your headlights every time you drive, and you'll drive with your regular headlights all the time.
I have retrofit projectors that I made... Acura TSX projectors. I decided to go without the Bixenon function because I don't care about DRLs.
...and Bixenon is more expensive, more complicated and I worried about the Bixenon fitting behind the headlight assembly, considering how tightly packed our engine compartments are.