A little help on cams

.. long overlap cams give poor cylinder filling and burning at idle and low rpm and that is why they are usually lazy until the rpm is higher.
raw gas is actually burning/popping in your exhaust manifolds and pipes
the unburnt gas at lo rpm is also going to wash your cylinder walls and give poor mileage.
they are for racing...
all info i have read or been told, i have no first hand expertise.