I dunno if it's true but I realized that bigger files, with same chunk size upload slower or something? So I have a harder time uploading a 20GB torrent with 4MB chunk size while it's much easier to upload a 3 or 4GB torrent with 4MB Chunk size. does that mean chunk size does not really matter, but your RAM struggles with big files, like a 20GB .rar for example or is it just luck? They both got the same amount of leechers and I doubt these types of factors are the problem...
Also is it possible to have chunk sizes below 256KB or above 4MB ?

Thanks!