200nl - What is the correct flop raise size and why?

[Lash]

Reads / History: Pf raiser is unknown - new to the table. SB is fishy – LPAS and gets tied onto marginal hands. UTG is LPAS. I have a somewhat TAGish image.

How much should I raise here and why?
Thanks

PokerStars No-Limit Hold'em, $2 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

UTG ($370.25)
MP ($160.65)
CO ($207.95)
Button ($244.35)
SB ($100.25)
Hero ($197)

Preflop: Hero is BB with 4[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/diamond.gif[/img].
UTG calls $2, <font color="#CC3333">MP raises to $4</font>, <font color="#666666">2 folds</font>, SB calls $3, Hero calls $2, UTG calls $2.

Flop: ($16) 4[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/spade.gif[/img], J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">SB bets $6</font>, Hero?