1987 GM Sunraycer by
Tyler Linner, on Flickr
Oldsmobile Aerotech by
Tyler Linner, on Flickr
1988 Pontiac Banshee Concept by
Tyler Linner, on Flickr
Notice that these all have smooth, rounded noses.
I taped the gaps on the Probe for awhile and found no noticeable improvement. However if the nose were reworked I'm sure it could do better. It's just that the time/money would be better spent making a full, smooth belly pan.