gmtruck828

9.3 breaks that option as well.

Not sure if I had mentioned this in my post, but my vibrations started well before I switched to 10 ply tires. I was running stock tires with no modifications to my truck at the time. Regarding the number of people affected, the GM service managers I've talked to have seen multiple trucks with these problems, even at smaller dealerships.

A few observations about my truck's vibrations: They seem to be worse with higher psi in my 10 ply tires. Once they get going at high speeds, it is hard to get them to stop and it feels like it is going to vibrate me off the highway. I've tried with the rear leaf spring clamps, can't say definitively whether it has helped. Anything messing with the suspension in the rear temporarily helps it. For exam, I have the Firestone Ride Rite air bags in the back. If I inflate them and raise the back of the truck, it rides without vibrations for several miles, but then they come back. If I let the air out and lower it back down, I have the same thing - no vibrations for a while and they they come back. They seem to be less severe in turns. Most of the time they are better if I keep it in M5 and tow mode, although they are still there. I can't figure out if the engine is unbalanced at low RPM's, or if the higher RPM's at a given speed are helping to counteract or balance out the harmonic vibrations. I've owned several GM trucks before. My last one had 200k+ miles and drove much better than this one drives now. I was aware of the vibrations in 2014's before buying my 2015, and test drove it extensively on the highway. It was smooth as glass for the first 1500 miles. The dealers have been pretty much worthless. I can't get them to return my calls, and when I drop it off they do almost nothing except drive it and say it is operating as normal. The last dealer said it definitely had the vibrations, but that they aren't getting enough money from GM to make it worth their while to work on these trucks. They have had several of them with no resolution. On the service write up, he blamed it on my aftermarket tires and leveling kit, even though I clearly brought it in with the same problems prior to new tires and leveling kit. This problem, and GM's lack of acknowledging it, are causing me to consider other brands for the first time. I have been very GM-loyal customer but this is all changing. My wife was in the market for a Yukon Denali but is now looking at Infiniti's, Toyota's, etc. I'm now looking at F-150's if I can't get the ride problem resolved.

I had the same problem with my 10-ply tires. Try putting the rear's at 32 and the fronts around 38. It seems to have helped mine some.

I installed iOS 9.2.1 beta on my iPhone and it didn't fix anything. It's really kind of frustrating because this was one of the few things that functioned flawlessly prior to the update.

Supposedly iOS 9.2.1 was going to have a fix, but I just downloaded the 9.2.1 public beta and I'm still having the same problems.

Everett Buick GMC in Arkansas will beat their price, and they were easier to deal with in my opinion.

I'm wondering how it would compare if there wasn't a leveling kit, just the body lift. I'll look around online. It seems there would be a way to change body mounts without doing a full body lift.

How much different would a 1.5" body lift look than the 2-2.5" leveling kits we are all putting on now? How much difference is the cost, and is there anyone that makes less than a 1.5" lift?

There's a diagram floating around here somewhere showing that the ground-to-fender height would lead you to believe there is a bigger rake then if you just measure the ground-to-cab height. I can't find the pic right now though.

One thing to remember is to measure from the bottom of the cab. I'm not sure the wheel wells will be the same height if the truck is truly level. I think the rear wheel well is cut out a little bit higher. I could be wrong though.

Thanks for the great information! Interesting that the dash speakers aren't just tweeters - although I am planning on putting components up front with tweeters in the dash. I wonder if the Bose front speakers get get a full range signal from the amp or if they are crossed over in the amp.

I've been looking at the JL 10" shallow mount subs. They have the best reviews for a shallow mount sub I've seen. Agree with buying new for subs.

Awesome, thanks. Can you hold the phone button on your steering wheel to activate Siri (as it currently works on my 2015)? Also, do you have to have a USB connection or does it work through Bluetooth?

How do you like it? Would you mind posting some videos of how it works? Do they offer a discount if you send your core back in, or would it be possible to sell your HMI to recoup some of the costs?