I have the early version of the Librands exhaust where the primary pipes cross over under the sump. This may be marginally more efficient, But it is a nightmare when you need to replace a leaking sump gasket. It is also prone to air leaks. The side exit primaries of the current system don't lose much, and are much easier to maintain.
Librands used to do two versions of the silencer , one louder than the other (not sure if that is still the case?) . I have the "soft" version and it suits the sort of motoring we do , ie long distance touring. If I was wanting to be more of a hooligan, I would specify the louder version.
However another couple of pieces of general advice. The resonators on the tail pipes do absorb quite a bit of noise so either make sure these are NOT included or be prepared to by-pass them , either by sleeving with a suitable solid pipe , OR better still using side pipes which exit in front of the rear wheels. The latter will certainly a lot of "brio" to the V8 orchestra, and is only really intrusive when accelerating hard or lifting off , at cruising speeds it is pretty quiet.
