My local garage I use for MOTs does a lot of vehicle modifications and it's these guys I'll probably use to install it also, let's face it - not exactly a hard install for any garage. So they will be fine with it they used to ignore my airbag light when the sprig connector went for my knee airbag.
Yeah I know it's v loud, personally I think it's the exhaust that gives the engine the best harmonics, I'll only ever have valves closed when I start from home though or hit my street up due to my neighbours being elderly with barky dogs.
They complain enough as it is when my friends stage 4 vxr comes and asbos up the place. Straight piped.... 😂