Originally Posted by MrSlik
What kind of midpipe do you have with the flowmasters? Stock midpipe with hollowed out cats or cats removed? Aftermarket O/R X or O/R H?
I had a similar experience when I first installed an O/R X with race bullets (perhaps a little different in my case given that I didn't have chambered mufflers, and don't know what type of midpipe you have). Sounded great, but had that ticking/rattling at idle when cold and trumpeted considerably right around 3000 RPMs.
A set of high-flow cats or perhaps bullet style muffler used as a resonator might slightly tame your exhaust just enough to stop the rattling at idle and high RPM without sacrificing a lot of volume or killing the exhaust note you like...
As far as I know everything is stock except what I've done to it myself in the past year. Midpipe and all of it. The cats were removed and just a piece of piping was put in it's place. I'm considering a muffler delete pipe to replace the Flowmasters to increase the air flow