A/c firewall plugs on ebay for some of you that dont know
 

these up on ebay states its only for s13 but it fits on s14 just fine. I was thinking at first whether to buy them or not but i looked at the price said what the heck let me give it a try. $10 bucks u cant beat it unless u have a welder and want to shut the holes permanently then its different story.
S13 180SX 240SX Silvia A/C Delete Firewall Plug | eBay