I am considering "upgrading" my VP180 v3 to the v4. I was told the following by Brent Tombari:
"The V4 products utilize die cast woofers, die cast mids, new die cast tweeters and have a new crossover. Die cast reduces heat build up which in turn raises efficiency and lowers distortion. The crossover offers smoother performance across the frequency range.
The HP version, upgrades the woofers and crossover and is designed mainly for high powered amplifiers. If you are not utilizing a subwoofer within your system the HP version would be a better choice."