It has as much to do with driving style as power/tq! As some has pointed out the shafts does not break by tq's alone but rather powerful jolts at the crank. I run 650 wtq without a problem but do not run 1/4 miles or races from standstill, this is what shocks stuff to breaking.
However increasing power will always put more stress on your car but that is nothing new. Also, See how many run FBO with no problems to drivetrain..
E92 335i 2007 black edition
Last edited by johmei; 10-04-2012 at 04:11 AM.