Keep at it Darth. After a year and a half, the Anax 3.0 aka Rabid Dawg part duex doesn't seem to be coming out any time soon. 

Well, I am done with the Tyll's mod... After trying out a lot of things, the best-sounding way how to use it in my experience is this:



Instead of using the whole pieces, I just use the small rectangular parts (in red, size is only an approximation)... It makes vocals as great as with no-dust-covers configuration, makes imaging at sides less fuzzy without making soundstage less wide or deep... and all the glorious detail is there (which is not true with full Tyll's Anax mod). The downside is that there is still a bit too much of air, making background a bit too grayish. It does not make imaging less apparent but you just hear a bit more gray background than would be ideal. Another downsize is that ringing is not reduced sufficiently... but IMHO it's not reduced any better with the full Tyll's Anax mod either so no change here.

Looking forward to try the Changstar version... But I am quite worried because people hyped the Tyll's version how impressive it is... and well, it is certainly fine but nowhere near perfect.

EDIT: Forgot to add that the overall tonality is still brighter than neutral... But that should be obvious.

I have found a difference between the two different shelf liners I used.  The thicker one was marginally better.

Fitting it in is a bit tricky.  I like to make the outside edge a bit bigger than the pattern so the pads press it down.  Seems to help keep it smoothed out and in place.  Also cut the inside hole a little smaller, get it to sit flat, then trim out the inside until it fits.  That has been the best strategy for me so far.  I have used a couple dabs of superglue to stick the liner to the foam but if the liner doesn't fit snugly it doesn't work that well.

The more complicated option that I have used is to roll the liner into a cone to mimic the tapered edges, cut out the bottom, trim the top to fit and then use a couple dabs of super glue to stick it together.  I can see if I can dig out the template I made, it isn't perfect but it is a decent starting place.  I gave up because it was to much work and I have found the other technique I mentioned works just as well.

I have successfully finished the Anax 2.0 mod about an hour ago... OMG, I don't wanna do that shelf liner part ever again! Btw, I would like to thank Stapsy again for helping me!

My first impressions (I doubt they will change):
1) Imaging is brilliant - as good as before at center and not diffuse at all at sides... Simply precision. This is the most evident highlight of this mod.
2) Airiness is not decreased, at least not to my ears, in comparison to stock... This is definitely an improvement over Tyll's version which lacked air. On the other hand, his version improved blackness of background which is not the case here.
3) Soundstage is absolutely fine in terms of width or height and depth also remains about the same as stock (not as good as with no dust covers)... So I would say a definite satisfaction and again improvement over Tyll's version which lacked depth (at least IMHO).
4) Tonality is the same as with stock headphones... I mean REALLY the same - not slightly more bassy and sibilant as with Tyll's version (at least this was my experience). This Changstar version definitely does not change the headphone - only decrease the peakiness... Meaning that these headphones are still bright and still very honest. They didnt transform into something more forgiving i would say - but you can hear that upper mids/lower treble are cleaner (especially gonna be appreciated when you turn the volume up).
5) Ringing/excess energy is definitely decreased but I can still slightly hear it... I am looking forward to try the Rabid Dog II because of this.

I wasn't impressed at all after listening to a song or two at first because my brain expected some kind of BIGGER change in sound because of all the waiting (for materials) and effort I put into doing this modification properly. But then you start to realise that this exactly was the purpose - the Anax 2.0 doesn't transform HD800s into something else at all - only subtle "adjustments" happen to reduce their flaws without changing the rest. I admire Tyll's articles and all his work for our audiophile community... But he should seriously skip his version of Anax mod and try this one instead - Changstar's version does its job significantly better. 

Leaving the dust cover on seems to help a little with the treble. You may want to try that.