text: GM to Boost Incentives in 'Red Tag' Sale  DETROIT (Reuters) - General Motors Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GM.N target=/stocks/quickinfo/fullquote"&gt;GM.N&lt;/A&gt;, coming off  two straight months of disappointing sales, told dealers on  Tuesday it will launch new U.S. sales incentives later this  week.