Since I noticed that you can upload soundtracks that are rare to find, how about uploading the two Metal Slug original soundtrack albums by Noise Factory? Specifically, the Metal Slug 3 and 5 ones. I found uploads of them on other sites but most of them are either on MP3 VBR V2 version or have no FLAC version at all. That is concerning to me as I'm more of a VBR V0, 320kbps and FLAC guy.
In fact, according to a certain review on the VGMO site, the reviewer mentions that he recommends the original Noise Factory versions for the Metal Slug 3 & 5 soundtracks instead of the ones found on the Complete Sound Box due to sound quality. Also, they are out of print and Noise Factory has already been defunct. Here are the links below to prove their existence.
Metal Slug 3 - Original Soundtrack: https://vgmdb.net/album/654
Metal Slug 5 - Original Soundtrack: https://vgmdb.net/album/657
If possible, upload them in either MP3 (320kbps, VBR V0 or both) and/or FLAC. In my opinion, this request is entirely optional. I can understand if you decide not to fulfill it as I don't mind it. That is all for my request.
Hey there.
We spent some time researching a bit and found the METAL SLUG 3 and METAL SLUG 5 Soundtracks are available for purchase on iTunes($11) METAL SLUG 5, iTunes($10) METAL SLUG 3, Amazon($19) METAL SLUG 3 and Google Play($9) METAL SLUG 5, . Listening to the preview, the sound quality is quite good. The iTunes version is 256kbps AAC, Amazon 256kbps MP3 and the Google Play version is up to 320kbps MP3(apparently, if you choose to stream the album Google lets you choose the bit rate up to 320).
It appears what you mentioned about the Complete Sound Box being lower quality compared to the originals is true(which is unfortunate because the Complete Box is easier to come across). Since the Complete Sound Box was released in 2006 and these digital releases we found were released just this year on March 27, 2019. I would like to believe they are from a more recent rip of the original albums. I couldn't find anybody to verify this at the moment but perhaps if somebody has the answer they could respond or shoot us an e-mail so we could let others know. I personally would like to see FLAC availability as well but the rare used copies we found were going for about $150.. Just a little too steep.
Hopefully this helps you out and feel free to let us know of any other OST's that you may have interest in.