I'm not sure how much HP I freed-up (maybe 10??).... but it sure is nice to just turn on the water pump and electric fan to cool down real quick after making a pass.
...that's the best part about it, IMO. That, and it cleans up the engine bay (looks good too).
You should consider using one of the restrictors/washers in your thermostat housing (moroso makes them) if you plan on taking advantage of what I mentioned. I use the biggest washer in the kit...
FWIW, I use a Meziere pump and love it!!