I asked questions here, watched every video I could find on YT, and read as much as I could about the GM exhaust options, and after much consideration I ordered the GMPP exhaust and had it installed today. Specifically the GM Performance Parts exhaust, NOT the GM by Borla exhaust. Some conversations online are vague about which one they're referring to, it can be confusing since GM offers three options - the GMPP exhaust, and two GM by Borla options (with and without black tips).
I tried in vain to hear them in person first, but ended up having to rely on video and written reviews and comments. I went with the GMPP version despite it being more expensive because some comments claim the Borla was louder (I only wanted a mild increase in volume), and because GM's own descriptions on their website qoutes "Helps increase power by up to 11 HP and 6 lb.-ft of torque" and "30% backpressure reduction at 300-g/s, based on correlated flow testing" but they do not make any performance claims whatsoever for the GM by Borla version. So the GMPP version appeared to me, based on GM's own description, to be an actual performance upgrade. I know it's unlikely I'll feel an 11hp increase, I primarily wanted a mild increase in sound, the qouted performance increase just helped justify the upgrade in my mind, but was a secondary consideration. I went with GM exhaust also to maintain warranty, especially since the new exhaust itself is covered under the factory warranty just as it were stock, not just that it wouldn't negate my overall warranty.
I plan on updating this post with a better review once I've had it for a few days, but based on a 20 minute drive home from the dealership this evening, I can provide my initial experience. For reference, I've owned my 2024 RST 6.2L since early September and put 3,000 miles on the factory dual exhaust before upgrading.
When I went to pick it up tonight, I asked if we could walk out to my Tahoe instead of having service pull it around so I could hear the cold start. Cold start wasn't necessary that much louder, but it was unmistankenly deeper and had more growl, then when idle slowed down it idled at about the same volume as stock, just a little more rumble. The service guy pulled it out front while I walked behind to hear, and at a slow creep it was almost as mild as stock. I left the dealership during rush hour, so I couldn't really get on the throttle like I wanted due to traffic, but it is definitely louder and much deeper when accelerating. Some of the reviews who claim it is "as quiet as stock" either didn't own their stock exhaust for long enough to get a frame of reference, or have a different threshold for what they consider louder. It's primarily louder in the deeper octaves though, which likely contributes to it's reputation for being mild for an exhaust upgrade. Due to heavy traffic I could only cruise at 65 mph, and it does rumble a little maintaining that speed, but I did not detect any drone. My initial feelings are positive, I think I'm going to enjoy it quite a bit. I did get one chance on my drive home to get on it, and it does sound great at full throttle.
