Keta -

Don't sweat the upgrades on an e7. They are a great reel right out of the box and really need no upgrade. If the Dartsnium drag eventually wears out, I would replace with the same stock drag, but you could also go with carbontex. Bearing upgrade is really not necessary and there is much debate as to whether or not it even improves performance. Spool upgrades? Never heard of anyone upgrading the spool on an e7. Bottom line, the e7 is a high performance reel without any mods. The only guys doing so are what are called "tuners," they're the guys that tweak their reels for fun just to see how far they can push the envelope of performance. Nothing they do is really necessary - it's just a hobby for them.