I just got my zeta III installed a couple weeks ago, and boy I'll tell you it was freakin uncomfortable when I first sat in it. I'm a bit on the heavy side as well being 6' 200 lbs with a size 36 inch waist. At first when you sit in the seat it'll feel really tight for the first couple minutes but then it kinda loosens up once you drive around. It's definitely a lot more fun now taking turns especially when my gf's in the car and I see her flying everywhere while my seat holds me in place..but sometimes it can give me a little too much confident
. It's also a mission to get in and out of these seats..and I don't even have the XL version.