As many others have done,my VCMuzzler was left on our 09 and it passed right through our EPA "we're killing our planet" Test, here in The People's Republik of Maryland.I assume you meant "remove VCMuzzler". It's kind of up to you. I've heard many stories of people either forgetting to remove it, or intentionally leaving it in and nobody has been failed on account of it as far as I know. The one thing that you should be aware of is that if you've already driven it today, then taking it out might cause Check engine light since the engine won't be stone cold when you disconnect it. CEL errors are a reason for them to fail you, I believe (we don't have smog checks around here yet). If you do decide to remove it and you get a CEL, you will have to:
1. Disconnect the battery for about 20 minutes. However, this clears all of your vehicle's self diagnostics, which they check during the smog check, so you'll have to drive it around lots under various speeds etc. so that the diagnostics can complete before you take it in.
2. drive it and shut it off a bunch of times, the code eventually will clear itself. I'm not sure how long driving or how many times you'll have to stop and restart your vehicle before the code clears itself though. It can take some time.
3. reschedule your smog check appointment.
Personally, I would just leave it in and go. It doesn't affect any of the self diagnostics they check, nor the emissions of the vehicle.