Headhunter tourney hand (X post from STT)

[Mez]

X posted from STT. Mostly bc I lurk here more often and want to hear opinions here as well.

$80 buy in, with a $20 cash headhunter bonus, 10 people started with 3,000 each, top 3 get paid, 3rd is $100. 5 left, blinds 300/600. I'm 2nd in chips with ~7K - 8K. I have a very tight image after not playing a hand for the first 2 levels and just doubling up with AA in my SB.

Folded to me and I have A6 [img]/images/graemlins/heart.gif[/img] OTB. SB is chipleader with ~12K+ - he is loose aggressive. BB is all in with only ~400 chips, plus his $20 cash Headhunter.

I raise to 1,500, SB calls. Flop is 3 [img]/images/graemlins/spade.gif[/img]4 [img]/images/graemlins/spade.gif[/img]6 [img]/images/graemlins/spade.gif[/img]. SB Checks. I bet 1,400. SB now raises another 2,400 to 3,800.

What's my action?