Like sal said, on a 3.7 for the cost its probably not worth it for the minimal gain your going to get. I would just install a high flow muffler and save yourself some $. To really get anything out of it you would need to get an intake and tuner also. But your talking a lot of money. If you really want a good gain just do a gear swap and install some 3.73's. that will still run you about a grand or more