question Vivo, the one with the stubby muffler only has one shock, doesn't seems really safe for riding.
Stubby used a different swingarm and bigger shocks (SYM Shark 150 Mono Shock) and later included a rear disc brake conversion...
Safe? So far, no problem.
This is the SYM Shark 150 with the original mono shock.
This s8 has a different mono shock mod... Not a DIY tho...