The VIS are excellent value and easy to fit. Just need to be careful with the piston seal and tapping the little button follower down to the correct height.....and the correct way round. There instructions show the button tapped upside down. The little protuded 'nub' needs to face the follower.
The reason I also recommend the IE pump is because they've considered the long term effects of running an unequal shaft diameter. Their piston shaft is the same diameter top to bottom as per stock as it's stronger. It also uses the stock spring for longer follower life.
So to answer the original 'best hpfp out there' question, it's the IE item. But erm, it's $999