Simple, i searched on eBay motors and found this for you,
http://cgi.ebay.com/ebaymotors/99-00-CIVIC-SI-SIR-CLIMATE-CONTROL-RADIO-BEZEL-96-00-EK_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem19b6415e3aQQitemZ110431919674QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
its the 99-00 Civic Si Climate Control Bezel (i think thats what they call it)
difference between this and the EX is that this one comes with amber backlights instead of clear/white in the EX this would be considered the upgrade.