I feel like I have read it all when it comes to butyl tape versus urethane... My glass guy is good, though I don't trust him like I trust myself. I meticulously test fit, measure. and plan before I do anything. He just slaps glass in its place as quick as he can and then on to the next job... My biggest concerns with the urethane is the difficulty of cutting the glass out if job was done wrong, or windshield cracks and needs to be replaced in the future, urethane ooozing onto places it doesn't belong... Also the set height can affect moulding installation... On the contrary my only concern with the butyl is whether or not it is safe for a windshield? Never heard of a windshield dislodging from hard braking or a wreck??? Spent 3 years building this beast, any input is greatly appreciated!!!