Melling does not have a high volume pump. They have a "better" pump than stock. It has better flow characteristics ie: less cavitation issues.
We are working on one that will be a high volume pump. The prototype should be done in a couple weeks. We scrapped the 1st unit as the cost was too high for production. The 2nd design looks like it'll come in at a good retail price.
Look for any updates on our website. We'll put a picture up as soon as we're done with it.