Yes of course torque is what kills the gearbox in most cases, and yes 3rd gear is usually the one which goes bang first, but I wanna try first how far can I go with it and when it break will get a decent gearbox.

400lb/ft is the aim yes, and at 3000 it would be fine. However I'm afraid the 0.48 (the greatest one for low rpm torque) just won't cope with agressive antilag, as EGT will go too high, even with water-injection. Has anyone ever had that setup (T34 with agressive antilag and water-injection) ?

Will use 803s anyway, with fully std engine, so I don't think I will be able to push more than 350bhp with the 803s. 30psi-32psi should produce the wanted 400lb/ft I think.

Again, a table with the rpm range of the 0.48 0.55 and 0.63 exhaust housing would be very much welcome.