I had one on my wagon back when my wagon was my daily driver. As mentioned, output was GREATLY improved at lower speeds/idle. I think I had it on there for about 15K miles with no issues of its functioning.

The only issue I had was cosmetic. Back then, I think only a chromed version was available. It didn't take long for it to start peeling and flaking.

What sidelined the unit was a busted bolt. The bolt that hold belt tension snapped off when I went to change a belt one day. It was an original factory bolt too. I had had it in and out several times over the 15K miles with no apparent issues. Then, one day, with very little effort, *snap*. The days of the wagon being a daily driver were nearing an end, so I just put a stock unit back on.

I still have the powermaster unit. I keep saying one of these days I'll drill and tap the hole so I can use it again.