FWIW - the instructions for Prestique Plus seem to have changed and
perhaps the product itself has changed. When our roof was done, they
specifically stated 6 nails per shingle. Now they say six nails if
slope exceeds 21/12. The website is now organized by state so I don't
know how they differ by area.

Their website:
http://www.elkcorp.com/homeowners/pr...cationspec.cfm

"All warranties are contingent upon the correct installation as shown in
the instructions."

"For a Limited Wind Warranty, all Prestique and Raised ProfileTM
shingles must be applied with 4 properly placed fasteners, or in
the case of mansard applications, 6 properly placed fasteners
per shingle."