Just a few of the threads discussing the Flowmaster products in the last few months, should be a good start...
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000754
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000790
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000774
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000764
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000698
_________________________
Tip: see if your question has already been answered before asking it. Try our handy-dandy search tool!