As anyone who has owned an N64 will know, the video output is the wrong side of average. Because the machine lacks RGB output as standard there's no easy way of solving that issue. With that in mind, the latest episode of My Life in Gaming's technically-focused video series looks at the various hardware modifications available.
By far the most interesting aspect of the video is the inclusion of footage taken from a system augmented with the aforementioned Ultra HDMI mod. The section is question comes up around the 12 minute mark:
The unit isn't out yet, and you won't be able to buy modded consoles from RetroActive - the company will instead sell the board to modders and resellers, who will install it and then decide upon their own pricing. If you're keen to be kept in the loop then point your browser here.