Dual valve springs, or valve springs with a higher than normal on seat
pressure, are used in a number of different engines, and they do help to
prevent valve bounce. However, any aid they give comes at a price, just like
anything else.

Having higher valve spring pressure places more load on the equipment that
opens the valve, such as the rocker arm, pushrod and lifter if you have
them, and premature camshaft lobe wear is the most common problem associated
with valve springs that are too tough for the intended use.

The basic question you need to ask yourself is how much time does your
engine actually spend in "valve bounce town", and if the answer is more than
a few seconds every once in a while, then you *may* benefit from a set of
new valve springs with a damper.

Regards,
Noddy.

Thanx Noddy, i hear your words.

Peter