I've heard a few besides my own. They seem to all have a wurring sound while idling, at 2200 rpms there is a metalic resonance and after that its pretty silent. You can hear it down shifting etc, but if you are into the boost you really can't hear it.
Great blower for peak power. The only problem I've found is that with stock pullies, the blower makes plenty of boost but it really pours on late in the band. If your wanted a broader powerband overall, I think it would really respond well to a smaller pulley moving the impeller speed closer to its optimum range. Of course then you would have to deal with ALOT of peak boost. You could also do what I did which is setup your motor for more low-end and the blower will take care of the peak.
My setup was a 300rwhp setup N/A, so when I added the Novi with stock pullies I didn't expect to see more than 8-9psi. Instead I got 12psi at 6k. Talk about power, the late power isn't all bad though. It gets you out of the gate without boiling the hides, then when your moving it comes on in a big way. Most races I win between 5-6k because it seems I'm packing a little more power up there than other blower cars.
Quality is excelent, brackets are some of the best around and it has virtually limitless potential, whats not to love about the Novi? Again if you want a huge hit on the low end you might want to try a KB or even an S-trim which comes on a little faster then the Novi but then signs off early. For me I'm very happy with the decision I made.
Later