Caution with mods to 09 SS
Gday FJJ,
I have owned many V8s over the years and 5 weeks ago I picked up my new 09 SSV (auto with active fuel management). If you have also purchased the auto 09, be aware that there are issues with installing aftermarket exhausts, as when the AFM activates, you effectively have a V4 engine breathing through the tubes, and hence an over piped system.
I had my exhaust done (2.5" cat back ) and the drone was dreadful at highway speeds. It has been back to the installer quite a few times for muffler alterations, cross pipes, etc, and in an attempt to fix the problem it now has hurricane headers and hi flow cats. The sound and performance difference is great, but it still carries an awful hammering drone inside the cabin when AFM kicks in. I then had the original factory mufflers put back on the new exhaust and the drone was gone....but so, unfortunately, was the V8 note and the performance. After searching a few forum sites in the states, it appears as though this is a very well known and common problem. Many in the states have given up and returned to factory exhaust. Others just drive in manual mode (which does stop the AFM activating. This works on mine too)
Interested to hear from anyone who may have experienced this problem here, and how, if at all, they managed to fix the issue.