105 without 103 with - at least thats what I recall mine being, but that also had a downpipe - cat will drop the dB's slightly.
You really want to get your exhaust down to 98dB at its absolute maximum to ensure you can get on track at most places, some are even stricter requiring 96dB
So you may struggle to get the nur down to an acceptable level. Even a drop in silencer dosnt do much to drop the dB's.
A flat plate with lots of perforated holes in it slipped between the mating flages of the exhaust is a good way to reduce the noise levels - if you make it into a long cone shape it can slot down inside the exhaust and you effectivley have a greater surfce area for the gas to pass through so it proves less of a restriction.
Mine registered 116 db the last time it was tested. Needless to say I was sent home and not allowed on the track that day.
My next system will most likely be the Burk
Mikejc