H1B COS - what happens when an RFE is not responded within the given time

I’m on LI Visa (valid till oct 2013). I have applied for H1-B COS and a RFE has been raised with the last date to respond to RFE on 10 Sept.
If I don’t respond to the RFE, will my h1-B petition be automatically denied ? And what happens in this case – am i legally allowed to stay in the country till oct 2013 (on L1) or do I have to immediately leave US ?

You can legally stay till October 2013 with your L1 Status. If you have plan NOT to respond to your H1B petition RFE. It is better you withdraw your petition before the due date. Do NOT leave as such.