I don't know about the HVH but I think it's close to the APD Black Widow spacer I have.

Scott has one as a Dyno Mule spacer and we tried it out during one of the builds and it showed a pretty good increase in both HP and TQ.

Enough to where I saved up the money to get one of my own.

I don't have any hard dyno numbers, but it did seem quicker by the seat of the pants test, lol,
Throttle response seemed better, and I had to jet up a bit,,,
I would try and borrow one if possible,,,,,

Thanks,Doc! How have you been?

On my friends 360, a 2" HVH Super Sucker spacer picked up 10ft/lbs across the power range. It also cleaned up the idle and the engine through the rev range.
It was a baic 360, factory heads, Edelbrock Air Gap, Flat tappet cam etc.

Years ago when I built the 465 for my charger we got the best power with a 1" hvh on top of a 1" open spacer on my street dominator intake.Granted it was a 525hp street motor but this combo bested every other combo we tried.

and like any spacer you will most likely have to rejet to get all it has to offer.

Not trying to hijack, but if you had to pick 3 spacers to bring with you to the dyno what would they be?
Kevin