When a new bike is introduced in the market, Arrow normally decides to design an after-market exhaust for that bike. Also, Arrow can also decide to fit a new product (new materials, new shape and the like) to an existing bike or to improve a range with the exhaust fitting an older vehicle.
In either case, the after-market exhaust system is normally designed directly on the bike/scooter/moped. The bike (in most cases completely original) is placed on a stand in one of the working stations available in the R&D and they start thinking (discussing?) on the best layout of the exhaust. The design is then transferred to a physical sample, thanks to the experience and knowledge of R&D technicians and engineers: the prototype is made piece after piece, using common parts, off-the-shelf parts and new parts made to fit that vehicle.
When ready, the prototype exhaust system is then tested and checked looking for power output, noise, emissions and also checking fitment to be OK. Sometimes it is needed to do some changes to have the perfect mix (i.e. between power, noise and emissions): after every change the prototype exhaust is then checked again to arrive to the final prototype, to be put in production and sent to the market as soon as possible.

Full race system with a choice of either stainless steel headers and collector or titanium headers and collector.  Can is titanium with a carbon end cap.