I also have the Soul X-pipe and slash tips. (along with their down pipe)
The Soul product is excellent.
I really like the way they do a one piece cast X-pipe.
I just went with a standard Dual Exhaust Tips from Porsche I believe...but I have ordered from Soul - Porsche 718 Boxster / Cayman Sport Catalytic Converter Downpipe . My installer who installs both FabSpeed and Soul products said to look at Soul Performance - as they have put a lot more research in behind the 718 than Fabspeed. Not to say anything bad about Fabspeed but talking with the people at Soul - I can tell they know the 718 very well. Should have this installed in the next week or so.