@wombat as you can see, this sway bar /bumper bracket issue is common with VS (and other pan-based replica Speedsters). Some have installed their sway bar upside down thinking the unweighted car (wheels off the ground) gives clearance to the sway bar, but once the wheels are back on the ground and suspension in operating position, the sway bar comes into contact with the bumper brackets (what's that knocking sound I hear whenever I go over bump?). This upside down application may seem to be a quick and simple fix, but this method makes the sway bar the lowest part of the suspension and decreases the car's road clearance significantly exposing the lowered sway bar to road obstacles (and unsafe) on rough roads (bumps, dips, speed bumps, road debris, etc.)
Your 2015 Vintage Speedsters (Kirk) does not have a narrowed beam (unless you specifically asked Kirk for them). Removing the bumper brackets is simple, un-bolting a few nuts & bolts, making the suggested modifications (notch) and re-installing.
You may be thinking well, I don't want to go through that process, I'll just do without sway bars. Then, you will miss the significant handling improvements that sway bar (front) and a camber-compensator (rear) provides. Night & day difference. 
I'm just saying...