VMAX intake manifold spacer?

anybody ever tried a VMAX intake manifold spacer?

is it just a gimmick?

thoughts from you engineer-types and theorists?

http://www.jcwhitney.com/autoparts/ItemBrowse/c-10101/s-10101/p-100000324125/mediaCode-ZX/appId-10450099/Pr-p_CATENTRY_ID:10000032412510450099

Carburetor spacers and throttle body spacers have been around for years, this looks like it's just a version of that same idea for modular manifolds. All they really do is increase the plenum volume of the intake manifold. Usually that really is good for more horsepower and torque at higher rpms, but you might lose some lower down in the rpms. Usually increased plenum volume is a concern for already pretty tweaked engines. I wouldn't bother with it on a stock 4.3 Vortec without dyno charts to prove what it does. It's not a scam like the Turbonator in any case, it's just not the first step in making more power in most cases.