Bob, I just looked at the installation instructions on FP website and can't find any reference of installing washers above the clip. I did find the washer comment in the Dynojet instructions, so that's where I must have picked up the tip.
http://www.dynojet.com/pdf/2193.pdf
BTW, FP needs to work on their website... it sucks.
Interesting tidbit from FP website... says that they no longer sell jet kits to people in California due to emissions.
http://www.factorypro.com/Prod_Pages/indexmake.html