<p>Two problems with such scenario:</p>
<ol>
<li>Building your EC in the senior or even junior is too late. Many EC are timesinks that do little to boost admissions chances.</li>
<li>Having to boost your GPA is also late, and is not an if/or proposal. Maintaining a high GPA is more or less a given. </li>
</ol>
<p>The reality is that the most effective and time efficient to improve an application is to hit a SAT or ACT out of the ballpark. Fwiw, those were the exact words I used to suggest to Curmudgeon that retaking the test on a Saturday might make a difference.</p>