it really depends on where you live light pollution wise. if you live in the inner city, light pollution and other filters may improve the view, but it might not be worth it. these are the two I own:1, 2 . these filters work by blocking out all of the spectrum of light except for light produced by nebulas and such. they come in a few different varieties, narrowband filters block everything but the faint light produced by specific elements (hydrogen and oxygen are the most popular). broadband exclude only light tat you dont want (these are commonly known as light pollution or contrast filters). I could pick just one it would be the light pollution reduction filter. it really darkens the sky, and makes bright nebulae like orion nebula "pop". and i can still get this result from living in a 7 on the bortle scale (about as bad as it gets for light pollution). but to see the really dim stuff (galaxies, emission nebulae, ect.) there is really no substitution to going someplace dark. with your 6in telescope, going to a 3-2 on the bortle scale, you should be able to see all 110 messier objects, and quite a bit more. however with my 6in scope living in the city, i can barely make out brighter galaxies like the bode and cigar galaxies, but Andromeda looks like a fuzzy blob with hints of dust lanes. long story short, there is nothing better than going somewhere dark, if you already do live in a dark area filters can greatly improve the view.