Well, i am currently playing with bow/bow builds and learning how things works, cause finally i was able to get Asylum bow ^^

IMHO penetration is crucial. Unlike magicka or melee builds, bows do not have extra penetration so depending on type of pve content: solo, 4-man or trial, you will need to somehow cover missing penetration, that could be somewhere between 12k solo (if you have source of major breach) to around 4k (with good tank with additional reduction), but usually be somewhere around 6-8k.

If you are playing Warden, you can use Stuhn on front bar - this set is really great and let all your skills punching with max efficiency in vet dung (regular dps 35k, not in dummy hugging) & i found it useful even in pvp (broke my first record of 24 kills ).

But if you are playing any other class, source of pen could be a problem.

If you wanna use your class skills, playing for example Necro you need to get sharpened bow that will give you 3k pen, and with Heartland Conqueror (which is also a great set) you can increase this bonus to 6k+. Plus as another bonus, if you will use HC on body, your backbar infused bow with weapon glyph will raise to ca. 550 dmg.

But if you are playing other classes that do not use class skills but rather rely on bow tree, like DK, Templar or Stamsorc, i would rather advice to take Asylum bow on frontbar - this will solve all your pen issues, let you choose precision trait and help you in keeping hawk eye bonus - weaving with other than bow tree skills sometimes get tricky

NB is probably most difficult class, as it is using mix of class and weapon skills, so you just need to plan it for yourself -_-

Of course you can try to cummulate penetration in other ways, using bosmer, taking sets like NMA, Tzogvin or Red Eagle or putting few light armour pieces (max 2 if you wanna use shuffle) but imho it is just too much micromanagement to keep a reasonable penetration - it is far better to focus on sets focused purely on dmg or crit. It is just more efficient. Plus you will not harm your sustain.

So Rele is a really good choice but if you want to optimize it, i will advise some good dmg set that will increase your winds power ^^, like Diamond's Victory (rele doesn't crit). DV works with Asylum bow and skills like warden bugs or NB reaper's mark or leeching strikes. Optionally Kinras as it will enhance Rele too.

But if you are going for crit build, i would rather ignore Rele and replace it with Yandir (SulXan is the best if you wouldn't mind to run for the ghosts and manage to keeping its uptime ^^). Then as a second set you can get Tzogvin or Dragonguard Elite (which is imho better than Tzogvin but it was always getting tricky with backstabber - to use both you need to stand in very specific place ^^ Now with crit dmg cap it is not so much issue now. Plus minor force you can get from FG light trap). This way you should have really good balance of dmg & crit, which is crucial for U32.

And of course backbar - the best option would be probably Maelstorm, unless your build can do a lot of dots - then Master could be comparable option.

But with those two sets + Asylum on front and Maelstorm/Master on back, you do not have much more place for monster set or mythic on most classes.

Basically only Warden and Necro can get this (with trial set on body+Stuhn on front OR trial set on front and HC on body), so you can use Slim+Kilt or monster. I am currently running Molag Kena, it is really easy to keep with bows, it works great with HawkEye and improve your Rele winds with additional dmg). Other sets are fun to use but in terms of dmg improvement, Molag is the best.