Keep it as simple as you can for the IVA, just build in any spare cables/hoses/mountings and fit after the test. You will have plenty of time to modify after the iva while waiting for the dvla to register the car
The silencers fitted to gsxr 1000 k4 have a cat inside the silencer so could be an option but you would need to prove it Bob to keep him happy.
Bob was very fair and realistic when he looked at my car, certainly one of the better inspectors - If you haven't seen it have a look at my IVA post. Beware he does heave a bit of a gripe about side repeaters and prefers them on the fron wings. He measured mine very carefully.