Brass fittings are so darn soft I often struggle to loosten them without damaging threading to some extent. Is there a trick to not damaging them? For example drain plugs on the bottom of the exhaust manifolds and engine...those with a hex fitting, only if these are loose do I stand a chance of getting these out w/o damaging them.

maybe spray first with wd or pb blaster. Other than that maybe some heat

I changed the pipe plugs on my headers to 1/4 turn water shutoffs so I can drain after each use. Works like a champ

Replace with stainless?

Get better wrenches?

Why so tight? They're only holding water in under basically no pressure?

Stainless looks nice but it galls, not a better option. I think someone over-tightened things

Use a socket or a flare nut wrench. If the flare nut wrench won't fit then heat it up and bend it to make it work. Put some anti-seize on it when you re-install.

agreed on the flare nut and anti-seize

It [i[can[/i] gall, particularly when you have SS fittings threaded into other SS fittings, but if you use quality plugs and some nickel bearing thread tape you should have no issue.