Yeah, tinkering for tinkering's sake is probably a bad idea, but then again, if you plan on tech-ing your own gun/s in future, you have to start somewhere. Depending on how confident you feel about your ability to dismantle stuff and re-mantle it, maybe better to wait until you have a back up before doing something which may need someone else to fix. That said I didn't - I only skirmished my CM.028U once before I had her in bits - it has to be said however that I did fuck her up too, although it took a few more fiddling sessions than the first - but until recently she has never been as good as she was straight out of the box, which is particularly galling because she was excellent!
The hop unit in wombat machines has a good rep and the green G&G rubber is above average. However I'd say that any AEG hop unit which uses a plain cylinder shaped nub will be improved for accuracy by an H-nub. It's a simple thing to fit, so long as you do it on a bench with enough space, or over carpet with a short shag/lino/tiles - because if you drop either of the nubs into deep carpet, or a pile of crap in a workshop, etc., you may not see it again.
If you do think of fitting a TBB, bear in mind that a 363x6.03mm TBB will increase your FPS with 0.2s by about 25, compared to a 363x6.08mm stock barrel, so you may find that if your local site limit is 350, you have to downgrade the spring - which is a whole different cupboard of monkeys. I would suggest going down to an Element M95 rather than the typical M90 (which would lose you everything you gained, and maybe a bit more, from the TBB).
