I a, swapping In an ls3 and have a question on two ports on the engine. There is one por directly behind the throttle body on the drivers side. Where does this go?
Same with the port on the drivers side valve cover near the firewall, where do I connect this?
Are these for pcv system? Can I just cap these off and not worry about them?
I already got the fresh air (I believe) line from the passenger valve cover to directly behind the throttle body on the passenger side.

Thanks

There have been a couple different pcv systems used on these engines, so plumbing will depend on what route you want to go. I opted for the internal corvette setup for its simplicity. in that setup, you run valley cover w/ integrated "pcv" 12577927. hose goes from the port behind the tb to the valley cover port. block off valve cover vacuum port on driver side and pcv (12568011 is the gm number for the pcv plug). run passenger side valve cover vacuum port to intake after maf and before tb. cleanest setup, no pcv to clog.

Ok that sounds good. Only thing is my engine doesn't have a port on the valley cover.
Can I just block off the port on the drivers side behind the throttle body and the one on the drivers side valve cover?
Would that cause any harm at all?

I can get pictures if needed as I'm talking about

If you're fairly stock you should run a pcv system, whether it be the stock ls3 external setup or convert to the corvette internal system. The valley cover is around $75, you'll never have to change a pcv again, and you will cut down on oil consumption (something these engines have been known to have a bit of an issue with). LS1Howto or LS1Tech have a lot of diagrams on how to run the setup

Where can I get the valley cover with the pcv system besides a dealership?
What would the cons be to not runnimg a pcv system at all?

I got mine off of eBay.

Not running PCV is not a good idea. You'll leave vapors in the crankcase that will contaminate the oil, leading to not good things.