Safe limit for a manual box has so many caveats
Hard launch or not
Health of the current box plus history of the current box
What is second and third gear wear and tear like
What will the power curve look like and how will it deliver the power to the box,,,,also remember its loosing traction that can destroy a box too
INMO If your gearbox is in good condition and you DO NOT implement too many hard launches, a manual box has to be good for 660 to 710 bhp but dont quote me
My box is a manual and has hed extensive works plus the drive shafts etc
At a certain power output, you need to consider going 2wd as the front diff cannot take the power!!!
Hard launch or not
Health of the current box plus history of the current box
What is second and third gear wear and tear like
What will the power curve look like and how will it deliver the power to the box,,,,also remember its loosing traction that can destroy a box too
INMO If your gearbox is in good condition and you DO NOT implement too many hard launches, a manual box has to be good for 660 to 710 bhp but dont quote me
My box is a manual and has hed extensive works plus the drive shafts etc
At a certain power output, you need to consider going 2wd as the front diff cannot take the power!!!