Make sure you read the online directions first. The little x on the tunnel are off so don't drill without measuring first. At least on mine. The directions even say to measure and not trust the marks, like I did, so they know they are off. I made a mess by not measuring first and assuming the x marks were measured correctly. Each side was a different distance from center to the side seam. Maybe mine is a fluke, but surprisingly different from left side to right side. So measure first. Lesson learned.
Regarding the bag, I've been out and used it a few times now. I love it. Slow to get in and out of (with the need to burp it when closing) but worth it for the waterproofness, volume, layout and expandability.
I wish it could go in position 1, like others say, since I rarely bring gas can. Silly that it can't.
Really handy that it can expand so much and the clamshell just adjusts taller to accommodate. It's a keeper!