feel like adding my 2 bob.
super t10, 400hp is on the limit. i know from first hand experinece, i have broken one twice, each time different problem.
yes they do handle alot of abuse but there is a limit.
they suffer from oiling issues.
to make them bullet proof you have to spent alot of money on them buying rollerized mainshafts, rem polishing and race syncros and hubs.
to buy a t5 that can handle power, you might as well not buy one for the price.
t56`s have there problems also which lead to self destruction.
value for money tremec tko is the way to go. i dont think its over kill for a 400hp engine, once most people have the taste for power they want more.
at the end of day you can break type of gearbox, (the driver has alot to do with this) so the major thing you must look for is parts availability
and can it some1 repair them.
lot to be said for the tremec once u have it should not have any trouble with hp issues..... 3000 for the box seems reasonable to sourse the other parts at better prices may be a a solution??