Split-grade printing won't help if you're already using the #5 filter. What might help is a #47 blue filter, which will ensure that you're getting only blue light to your print and therefore max contrast from the VC paper.
One of the first things I'd try, however, would be to expose and develop a print with your safelights off to ensure that you're not getting lower contrast due to safelight fog.
Also, some brands of paper are contrastier than others. You might try another paper if you have one.
Other things to try:
Stronger, higher-contrast developer. Straight Dektol or LPD will give a tad more contrast than diluted. Intensifying a negative is not so difficult. If you have a neg developed in a non-staining developer, a 5-minute treatment in selenium toner diluted 1+2 will give you a 1/2 to 1 step contrast increase. This is very gratifying sometimes. If you have a pyro-developed negative, then bleach/redevelop is the way to go.
Selenium toning the print will bring up the D-max a little. Print for the whites and tone a print and see if it helps enough.
Bleach in a rehalogenating bleach of potassium ferricyanide and potassium bromide until the silver image is completely gone (only a faint dye image will remain). Then, redevelop the negative to completion in a staining developer (e.g., PMK, Pyrocat). This will add stain image to the redeveloped silver image giving more contrast. This technique is gratifying to use as well.
Bleaching highlights as mentioned above can give more contrast to a print and is a good tool, especially if there are only a few areas of real highlights that can easily be bleached up locally (clouds, specular highlights, etc.).
There are other intensifiers, but they are more toxic and less predictable; I don't use them.
Best,
Doremus
