@TantrayaanWith an 8.5 rating, you really can't get much better in terms of scores. However the best way to control reader involvement is a 'schedule' your posts. Typically if you only post once every three months, or post irregularly, then your overall scores, the number of downloads and reader feedback tend to fall off.
So what works better—at least on SOL—are shorter chapters that post on a consistent regular basis that readers can anticipate each post, driving up their excitement. Thus when it's scheduled to appear, your readers will be actively waiting to devour the latest chapter.
Personally, I've always found between two to three chapters per week get the greatest response, though a story that posts regularly once-a-week will do nearly as well.
However, if you haven't planned ahead, and are just writing/posting chapter by chapter, largely as the inspiration hits you, then you're downloads will main fairly low, as will the reader feedback.
Readers are impatient, so if they know how long they have to wait they'll respond better. Otherwise, as has been noted, most will just say "Screw it, I'll wait until it's done before even starting." In short, regular posts signify a 'plan of action' and usually indicates a story written in advance, so readers tend to trust those over the may "Will they finish they story or not" postings.
But again, there's a big difference between downloads, sales and reader feedback, so the three are best considered individually.
Also, as an aside, the best way to get greater feedback is by actively engaging it. So specifically asking for feedback in the story description is the best start, as is asking for corrects and/or suggestions, as that gets a reader/author dialogue going. Then, you have to followup on it, so that if readers bitch about something, you'd better address it or it simply sounds like empty promises.
However, some changes take longer than others, so if you merely acknowledge the issue—especially in the story itself—readers will assume you're working on it and will then trust you to fix it in your own time—as long as you actually do it, that is.