Welcome to the forum, with the sinking clutch pedal, its most likely the slave cylinder, or this would be a good starting point, we do a kit with the slave, line and fluid...
This methinks. When I had a zorst fitted I'm sure they had to remove it.
Was it a Scorpion system, as this part does indeed need to be removed to fit the Scorpion...
Exhaust system goes manifolds, cats, Y pipe, mid pipe and rear silencer, resonated means quieter and non resonated is louder, let us know if you want a new exhaust...