i have had a detroit locker in the rear for 2 years and i will never go back to a cheap lunch box locker or spool. but to answer your question yes at first it will seem like it twist but its not harming anything. the twisting effect you are feeling is all the torque being sent to the power wheel in the rear and with soft springs you will feel it move alot more...
i have ruf and soft worn out mazda hybrids in the rear and from a stop the front will lift slighty and the rear want to keep going,kinda causing the twisting effect you might be experiencing.
hope this helped..
