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. 
Stephentp I just took delivery of the Lawton Audio tuneup kit and replacement cups in museum grade Mexican Bocote for my Fostex TH900s .
It made a significant difference for the better that’s for sure . 

Thansk for your response.  Did you by chance get to sample the sound comparison with TUNE UP with the stock cups?  I don't plan to change the cups.  Best!

Also, are you using the stock TH900 cable or upgraded that too?
Stephentp I immediately noticed a very positive difference installing the Lawton designed damping rings , the wood cups are a definite bonus further refining the sound and they do exactly what the manufacturer claim . I purchased the TH900 slightly used with Moon Audios top silver cable installed.

I’m fairly new to using headphones and headphone amplifiers I borrowed a few to try from an huge headphone enthusiast . The Lawton upgrade package was a shot in the dark I thought I’d try and happily it worked out very well .
in_shore, thanks for that insight, I'll probably get the work done after your review.  best!