Hi Energy vs Pro Magnum HFT lifters

Of coarse they will (may) pull more manifold vac, they are reducing your duration and lift as they bleed down. The fact that you say the wire clip or C clip as I mentioned in my previous post can pop as a result of valve float , proves my point. You don't fix valve float by replacing the lifters unless you put lighter ones in there and reduce the mass acting on the weaker valve spring. And you don't need anti pump ups if you have a stable valve train.
Have a nice Xmas too.