The slip on connections are fine, and allow you to tweak the position of the extensions. I would not use a U-bolt, as they screw up the pipe for good, and you need to heat them with a torch to get them off. I use Donaldson Maxi-Grip bent bolt clamps on the roadster and 40, both with Red's headers and exhaust extensions. I have had the exhaust system off and on several times and they come apart easily and go right back together. I got the tip off on the Bent Bolt clamps here on the Barn about 10 years ago. Best thing I ever did for an exhaust system.