My Detroit Locker does make some "noise" at really low speed turns and maybe right after putting the car in "Drive" from Reverse (like when I back out of my garage and onto the street), but not bad... Driving around town, I have never noticed any issues...
I drove the car throught the mountains (I-80) at 65+ and never had an issue... i got caught in a heavy thunderstorm coming back from Reno, and although I "white-knuckled" it (because of the locker and the rain, and stories I heard), it actually performed great, with no issues...
But I agree with some of the others, at your power level, I wouldn't buy one.
The previous owner installed it, and I have been considering a Tru-trac or clutch-type (I also wanted to change the gear ratio too) because I think it might be a bit overkill for my car (plus I want to try some autocross, etc)...