Should I upgrade the wicked wheel in my 99 f450 6 speed? I've just ordered a set of gauges and a php 6 position chip. The truck currently has a 4 inch straight pipe and an airaid intake .

 

Wait till you get your new stuff and install it. If your turbo isnt surging, then no, because the original WW doesnt have any increased performance over the stock, just protects against surge. However, if your trubo does surge then yes, get the WW. If you want a higher performing wheel without upgrading your turbo, then get the 2nd gen WW aka. WW2 or Billet WW.
Another cheap turbo upgrade to increase performance and protect against surge is a ported housing. ATS makes one as does Banks and some other companies.