I'm glad to know this too, as I was planning on building an 18v addon originally.
Does anyone know anything about this:
more than 25000 different guitar effects pedals from 4000 brands: vintage, modern, boutique, rare,...
www.effectsdatabase.com
"Based on our acclaimed PolySaturator design, the War Hog ups the ante with more gain and shifted EQ points to satisfy shredders"
That one does have "18v" printed in it, instead of "9v-15v"