Well it's definitley a good mod for the M52 engine. It gives the engine 40% more airflow and increases HP through the higher rev band for more top end power. Torque loss can be counteracted with under drive pulleys. I use the UUC motorwerks ones. In combination with te pulleys and a manifold you will notice an increase in performance. As for the throttle body, both the M50 and M52 throttle bodies are the same. You can use your M52 throttle body with the manifold.
The best kit out their is www.m50manifold.com
. I have heard lots of good thinks from that one, and their is excellent customer support of you have install issues. It will look like a factory install.