Is the Lawton tune-up and/or wooden cup replacements worth it ?

I have a pair of Fostex TH900 closed-back and pushing them with a good headphone amp.  More power than i need. Sometimes the highs and screaming vocals get a little muddy.  Would the tune-up offered by Lawton for $100 make a difference  as claimed?  And would the wooden cups they offer make an improvement over the stock wooden cups on the Fostex?  I've read all the insights from the Lawton website. Looking for a non-biased low-tech opinion if anyone has one.