The mandatory mufflers will be needed this friday.  You may use a different muffler if it is as quiet or quieter than the suggested part# 17702.  Be warned, track officials, not the club will be enforcing this rule.  I know there are at least 7 of these mufflers available at Advanced Auto Parts on Circle dr Cicero.  Please be prepared......for older motors that may experience starting issues, going to a 3 inch in/out muffler should help. just be sure hat tey are teh same configuration as the 17702. meaning you cant see straight through the muffler, If you have a clear view end to end. 99% chance it will be too loud.