ZM80D-HP and SLI queries

I'm looking at doing two things - finally getting round to doing some overclocking on my system and upgrading my trusty 6600gt. Because I only have so much cash, I was wondering about the viability of an overclocked sli option - two cheap Inno3D 7300gts (come in at about £140 from dabs for those fancy ddr3 cards) and some passive cooling courtesy of ZM80. Has anyone tried two of these side by side? More to the point, how easy is it to overclock sli set-ups?

I'm not entirely sure if you'd get any, let alone much, increased performance from 2 7300 cards at all.
If you were to overclock them in SLI, you'd be limited by the clockspeed of whichever one overclocks less.

This particular card does seem to overclock reasonably well, which is why I thought it might be viable (and fun!)

http://www.ngohq.com/home.php?page=a...age5&arc_id=86

http://www.trustedreviews.com/articl...ge=7222&head=0