Installed the longtubes with OR "Y" pipe(no cats) on my 09 Silverado Crew Cab(5.3 gas engine). I have 3 tips to make this job easier for anyone installing longtubes on an 09 or newer Silverado and some of these ideas will work on the older trucks too. 1: It helps to remove the plastic wheel wells. I used Stage8 header bolts so being able to reach through the wheel well to install the bolts, tabs and clips as well as the spark plugs and wires was easier from the side than from the top not to mention it cuts down on the bleeding caused by scraping your hands and arms on all the razor sharp clamps. 2: The header flange is slightly larger on these new style headers. I didn't find this out until I tried to put the oil dip stick tube back in. If you put the oil dip stick tube bracket flush against the head the hole for the bolt doesn't line up with the threaded hole in the head because the larger header flange moves the bracket over to the side. I had to grind down the bracket where it was contacting the header flage enough to get the hole in the bracket to line up with the threads in the head. I did not have this problem when installing longtubes on trucks built before 09. 3: The transmission support cross member is held in place by 4 long bolts(2 on each side). The inner bolt on the drivers side is too long once the "Y" pipe is installed. I ground about 1/2" off of the end of the bolt to get it to fit. Couldn't saw the bolt because it was too hard.

 

Great tips.