There are two instant upgrades that I recommend:
The first is an optical hdmi cable. I would have to search my earlier post to get the link, but it was a Monoprice cable.
The latest (and the trigger for this post) is a power filter. I had purchased several of these to use in my audiophile style music production home studio and the benefits, to my ears, were very nice. Clarity and sweetness are greatly enhanced, ear fatigue reduced. I decided to try one on the projector, not expecting any change.
I suppose I should not have been surprised, because the "clarity" was visibly improved. By this I mean that color purity seems to be increased. Subtle color distinctions are suddenly visible, lending to a delicious cinematic rendition.
Current price for this? $179 US. Well worth it in my book. I am currently using several of these in my system, one for the projector, one for my Digital Audio Interface, and one for the power amplifier that drives the speakers. Could you plug everything into just one filter? Yes, but I have found that you get extra (obsessive) benefits by isolating each component from the others. More benefits for keeping the noisiest components from the quieter ones.
I would say, try one and see if you like it on the projector.