The key word here is SAID!

 

So what you're saying is that you take off from a stop and as you hit 1500 it vibrates? That's not how I pictured it from your description, now it doesn't sound right. I would get another opinion on the mounts, it's not unusual for the factory to install them without the correct tolerances.
Maybe it's not related, but someone I know just got a new SG. It vibrated so bad at 50 mph she couldn't stand it. It was smooth as silk at 80. Bike was at the dealer within 500 miles and she was told it was normal. An experienced rider, she knows better and I'm waiting to see what happens.

 

Just my 2 cents, but I don't think that is normal, and you are not lugging your motor. At least on my EVO it will pull from 1500 without lugging it in 3rd and 4th. I do ease the throttle, and don't push it wide open. Harleys have almost full torque right off of idle. These things are tractors. I have been riding around town in 4th at 35 MPH in town for years without problems. Keeps my drag pipes quiet.

 

I'll bet it does.

 

I know it's not normal as said not my 1st hd and have been on prob 50 different bikes at least 5 2011-2012 103 flhx and none do the same but Harley and dealer say it normal

 

If its "normal" ask your dealer to test ride another on the floor. If that is not cool with them ask them to "test" ride one of the rentals. If they do not want to let you do this, they are not "normal".
Another thing that caused vibration on one of my touring bike platforms (soory I cant remember which right now) was a binding in the exhaust hanger. We loosened up all the connections shook it a bit and retightened and that made all the difference, was bound up and transfering vibs to the
chassis.
I know these suggestion are shots in the dark but they helped me so maybe you too??

 

I had that problem with my bike. The dealer gave me the usual "it's normal" run around. Then I did the exhaust and the problem went away.