No, not Bill here, but bought my '01 from him.
First, some '01 cars had low oil pressure episodes when new. I did, changed the oil and no more problems. I am going to guess someone was too generous with assembly lube at assembly. Has everyone done an oil change and made sure the oil pressure is over 40 psi at cold idle (and near 40 hot?). Low pressure can cause valve clatter with hydraulic lifters.
I now have about 3K miles on my car and have had 3 other Vipers (still have the '93). There may be some more valvetrain noise in the '01 than earlier cars, but I am not sure. This car is so much smoother and quieter everywhere else that this sound may appear accentuated.
In any event, it does not worry me. The car runs & drives fine, uses no oil, makes good power (119 mph in the 1/4) and so why worry? In fact, I miss my neutral gear rattle and the idle lope of the earlier cars.
If Dodge is forced to take too many rough edges off the car due to noise complaints, we are going to end up with a real marshmallow car, guys.