And how long time have you been doing that without issues?

Personally i think the durability and lifespan of the gearbox, has a lot to do with the way the car is driven, but i would like to hear your experience about this.
Maybe i'm totally wrong? I have not covered enough miles in my own car to have any experience with this, but i am aware of the problems i could or should i say will get? when running 400-450 ish on a standard box. So honestly i'm thinking about running with a lower boostpressure until i can afford a decent gearkit upgrade.

 

i ran that on my old ecos and is fine unless you launch it alot am going skyline box in my mk1 now

 

Its 3rd gear that the torque gets too & causes issues.

 

i was running 400bhp on a standard mt75 box no problems!! like someone else said its the way its driven that helps, and im not a slow driver but just didnt launch it at every junction!!!! by the way its rwd now Still got the box and it will go back on if i get bored of rwd!!! mmmmm maybe not then!!!!!!

 

It depends on the tolerances on the gears... many miles on the box is more backlash between gears so this makes it worse...
Most common issue however is 3rd gear and sometimes the 2nd gear... I have 400bhp and 520Nm of torque. I don't launch it off the line like a lunatic and I change gears slowly but I have broke 4 times the 3rd gear and most of the times with the engine at about 5000rpm... It has to do with torque and rpm imo mostly and not bhp...
what i did was to install an aftermarket boost controler and I made the car too produce boost without spikes and it helps alot, doesnt feel the same as before when you nail it but I am protecting the gearbox until the installation of stronger gears...

 

i have had 3 gearbox's go on me when driving normal.

3rd gear all the time.

 

Running 400bhp with standard box and no probs so far.... Just wait for it to blow up now!!