The Arrow Thunder for Aprilia RS 124 in Euro4 standard replaces the original underfloor rear silencer like the previous Euro3 silencer. Basically, Arrow also places the rear silencer under the engine, but adds an additional stainless steel pipe which ends just below the swingarm for a more sporty look.
The rear silencer itself is made of simple aluminium, as relatively little of it is visible. The visible pipes are made of stainless steel and therefore rust-free with good care.
This article is ONLY the single aluminium rear silencer from Arrow. To mount the rear silencer you need an intermediate pipe with catalyst (51013KZ). The complete exhaust system can be found under 51515AO51013KZ.