I have the Helwig bars front and rear on mine and could definitely tell a difference after installing them. Front is 1-5/16", rear is 1-1/4" solid chromolly.

TX has the Hotchkis bars which are hollow 1-7/16" front, 1-3/16" rear.

 

So I got to do some data logging and riding today. It may just be me but it feels like the rear shocks and springs are about to do their jobs better. It doesn't feel as "boingy" as before. Just smooth. Then A mustang decided he wanted a piece as I was rolling down 17 going to base. I let him get to my rear bumper (he was trying to ricer fly by me) then I nailed it and hit the high boost switch as I Was switching lanes. About 70mph as I'm switching lanes the rear felt like it had a real fast fish tail. Not a big motion it was very slight but was happening real rapid. At about 100-110 it wen away and I stayed in it. After I put a few busses on him I let out logger said 145mph. It felt real smooth at that speed. The guy turned onto base and smiled and gave me a "wow" kind of nod.

It feels like it is lifting the front a little more. But it may just be the cold *** weather letting I make more power. Not sure.

 

i was thinking about the hellwig 1.5" front bar and 1.25" rear bar. i seen at one time they had adjustable ones that i really wanted. but i can't find them now.

 

Look on Hellwig's app guide for an Avalanche. Same bar for the SUVs but it is adjustable. I don't recall the pn but my rear bar is adjustable.