Polaris Inc (PII) could be a solid addition to your portfolio given a notable revision in the company's earnings estimates. While the stock has been gaining lately, the trend might continue since its earnings outlook is still improving.The upward trend in estimate revisions for this snowmobile and ATV maker reflects growing optimism of analysts on its earnings prospects, which should get reflected in its stock price. After all, empirical research shows a strong correlation between trends in earnings estimate revisions and near-term stock price movements. Our stock rating tool -- the Zacks Rank -- is principally built on this insight.The five-grade Zacks Rank system, which ranges from a Zacks Rank #1 (Strong Buy) to a Zacks Rank #5 (Strong Sell), has an impressive externally-audited track record of outperformance, with Zacks #1 Ranked stocks generating an average annual return of +25% since 2008.For Polaris Inc, strong agreement among the covering analysts in revising earnings estimates upward has resulted in meaningful improvement in consensus estimates for the next quarter and full year.The chart below shows the evolution of forward 12-month Zacks Consensus EPS estimate:12 Month EPSCurrent-Quarter Estimate RevisionsThe earnings estimate of $1.52 per share for the current quarter represents a change of +590.91% from the number reported a year ago.Over the last 30 days, the Zacks Consensus Estimate for Polaris Inc has increased 57.13% because three estimates have moved higher compared to no negative revisions.Current-Year Estimate RevisionsThe company is expected to earn $8.41 per share for the full year, which represents a change of +8.66% from the prior-year number.In terms of estimate revisions, the trend for the current year also appears quite encouraging for Polaris Inc. Over the past month, six estimates have moved higher compared to no negative revisions, helping the consensus estimate increase 13.01%.Favorable Zacks RankThanks to promising estimate revisions, Polaris Inc currently carries a Zacks Rank #2 (Buy). The Zacks Rank is a tried-and-tested rating tool that helps investors effectively harness the power of earnings estimate revisions and make the right investment decision. You can see the complete list of today's Zacks #1 Rank (Strong Buy) stocks here.Our research shows that stocks with Zacks Rank #1 (Strong Buy) and 2 (Buy) significantly outperform the S&P 500.Bottom LineInvestors have been betting on Polaris Inc because of its solid estimate revisions, as evident from the stock's 21.3% gain over the past four weeks. As its earnings growth prospects might push the stock higher, you may consider adding it to your portfolio right away.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Polaris Inc. (PII): Free Stock Analysis Report To read this article on Zacks.com click here.