My problem with the 4000's is that the high beams on the 80 stockers are pretty good. A couple suggestions. First, try putting in higher wattage bulbs. IIRC, the 4000 uses a 55w bulb, try the 100w. If that doesn't help, I'd go pencil beam.
As a rule the driving/euro beam will give good filll to the stock lights, but IME (and I have a few posts here on this already as an ex rally guy) the inner highs on the 80 are pretty darn good, the low beams could use some help tho.
What might also help a bit is aiming them out. The inner highs are aimed pretty straight forward, so if you also aimed the 4k's that way, you will just create a more intense, or just overlapped hot spots.
I'd suggest moving them outbound of the high beam hot spots. The best way to do this is with a couple pieces of cardboard to cover the stock lights (esp if you have the 4k's wired to the high beam switch) and aim at the side of a building in a industrial park. Put the hot spots of the 4k's just outbound of the hot spots for the stock highs, and you should get a good beam spread. If you are after lighting further down the road, or to make the direct in front lighting hotter, then get the pencil beams.
IME with pencil beams, they are a high speed light with limited on time. #1 is traffic, you'll get flashed a mile back. #2 is they are highly reflective of humidity and road signs both. You buy the HID 4k's, make sure you mount them really well. We lost a couple at a rally, those are expensive and highly desired. Even the riff raff knows a good light when they steal it!
SJ