I'm left handed and in wondering if they make ambi-mag realeases for sigs.

Yes the Magazine release can be switched to the right for you lefties.  It is not ambi, but you can either have the release positioned on the left or right side.

     I'm a lefty too.  I am nearly certain the  229 and 226 mag releases are reversable.  I don't believe there are any ambi mag releases available.  My question is, why do you want one?  The SIGs to me are probably better for lefties then righties.  The decocker and mag release are in the perfect position to be operated by the trigger finder of a LH shooter.  IMHO, a rightie has to move their grip a bit too much to decock and drop the mag.  I've got pretty big hands too, and I can't do it.  

later,
AJ

Well, I didn't mean to say ambi :) I was just curious if it could be put the right side of the pistol. Do you need to buy any parts to make the switch or do you just reverse it or what?  You say your a southpaw and have no problems with any of the controls on a sig? Well that makes me happy because i've heard that they are not lefty friendly and i really like them. Guess when I get some money i'll head to the range and rent a sig to see how it feels.

The sticky at the top illustrates the magazine release reversal on a SIG P226.  

I'm lefty and prefer to keep all weapons setup righty and have never had a problem. Train that way and you'll be fine.