Simultaneously enable gzip and $STR_REPLACE in CGI in apache

I have a code in my CGI script for text replacement (for example replace 'red' with 'blue')

$STR_SEARCH='red'
$STR_REPLACE='blue'
I am using the below code in .htaccess for enable replace function: (RequestHeader unset Accept-Encoding)

This work fine. But when I want to use gzip for compression, gzip does not work. If I disable the replace, gzip works fine. Please help me understand how I can enable the replace and gzip simultaneously?