If you go plugs make sure you use FCS fusion not the old single plugs. I've destroyed a couple of the single plugs using MR twins. I haven't damaged a fusion box yet but I have still snapped fins off at the base laying into a bottom turn. Glass ins really are the best option for a dedicated twin.

Your other option would be fin placement similar to a twinzer so you have a really tight cluster. This surfs very similar to a twin but spreads the load over four tabs instead of two. Loose as a goose like a twin but still has that quad "powerband" when you pump a little speed turn.

I meant to say before I can't comment on Futures as I've never used them. This is what I meant by the tight cluster. If you want more drive swap em round and put the bigger fin in the rear.

Was just to illustrate the point chrispy. I usually surf with the larger fins in the front.

I have twin fins with keel and conventional fins. Both work. The keel appears faster down the line, but the conventional fin releases better out of the lip and has a tighter turn radius. I would also recommend channels, although quite shallow ones and not the full deep six. My three twinnies are all glasses in as are the four copies that have been made of one of them. And the rubbish about twinnies spinning out? Put those babies on rail and push as hard as want with your back foot. They won't budge a bit.

Plugs will work in the twinnie, you just need to add a little strength to the EPS foam. If divinycell foam is added to area the plugs are going and then the plugs are glassed in, this will provide the strength required.

Check out this web site boardlady.com/anatomy.htm and how to use composite construction techniques to add the strength