Hey,
Today I just bought a brand new Tremec TR3650 5 speed manual. The gearbox is rated at 360 lbft so it should handel my target 350-400hp. The gearbox is the one found in the BA ford falcon xr8 (which has a 290kw version i think)(it's an aussie car btw). It has the same input spline as the T5 and pretty much bolts right up to the 5L with minor modifications. The box cost me only $900AUD from a ford dealership, i am F@#$$ happy with it.