Of the two I'd take the Leo Vance. IMO the welds on the GPR are nasty, just my observations.
Personally I like the look and sound of the Arrows.
That said unless it's all about sound there is little value to adding just an exhaust to a 4 stroke scooter. Been there , spent the bucks and sounded good but it was my first and last.
All the best with it.
AMAC