I've been running over 400hp/600tq with meth on stock turbos with no issues whatsoever. And my car is nothing close to high maintenance, nor does it have a "ton of upgrades". Also, my meth system requires no maintenance aside from filling the tank
Those who are worrying about the transmission on these cars need to venture over to the gas forums a little more.... I just had a 600+whp N54 awd auto in my shop the other day and he beats on it all the time with no problems. These transmissions can take a lot more than they are rated for.