BTW, what's different about your tophat vs SDI? It would to good to know your design and your thoughts behind the design choices.
That is a good question to be asking. The most obvious difference when looking at a truck with each side by side is that our top hat lifts the front 0.5" less. Both do a similar thing in that the lift is one part spacer and one part preload. Our top hat is approximately half the preload and, I would guess, similar in terms of spacer. I don't have CAD for the SDI top hats so I can't comment on what their dimensions are exactly of course. I just felt like being a little more conservative with CV angle since I drive my truck every day. Also occasionally carry a snowmobile in the bed and don't want to look too nose up with that in there.
In terms of construction, our top hat uses the same bushings as the stock top hats. Not sure what bushings exactly the SDI ones use. I actually really like the stock bushings because they have a metal puck in the middle that makes it physically impossible for the shock shaft to come out of the top hat even if the rubber fails. I like good fail safes like that. What our top hat has that's different than stock is a much beefier retaining ring holding the bushing in since the retaining ring on the stock top hats is what I've seen actually be the root of problems. It would take about three times the weight of the truck to rip one of the retaining rings out of our top hat. Our top hat is also the only aftermarket top hat I'm aware of that actually uses pressed knurled studs. I wouldn't say that's a big deal, but I think it's kind of nice because they are bomb proof. Going back to bushings, made the choice to use bushings as opposed to uniballs for two reasons. First is uniballs just don't last in Washington. Too much water and grime especially driving mountain passes in the winter. Second is uniballs just aren't intended to be loaded axially. It can work, but you aren't guaranteed smooth motion under high load.
