You want to be more concerned about the torque than the bhp, but in the figures your talking about mtx is the way forward, if you can afford to get that sort of power out of that engine then you can afford a proper gearbox, ive dealt with a few customers who have done the conversion themselves with the focus rs box, its not as daunting as people think.

I have a cts s2+ box, my engine is being built with 250bhp with a shed load more torque (zvh) so that wont last 5 mins with my right foot. Be under no illusion that so called uprated boxed are not really any more uprated than a standard one i.e. the gear set will always stay the same.

Something to bare in mind if people quote you big figures for an ib box

If you need any more info give me a bell or email as I have done some good research into this