Why does the standard CAT on a 1litre micra have an exit bore of around 70mm when the exhaust connecting to it has a much smaller diameter (around 30mm). There is also no taper to the smaller exhaust pipe!!! This will be harmful to exhaust exit speed!!! I have just connected a side exit straight through exhaust from the cat back and was surprised at the size of the cat compared to exhaust.
Apart from a back box, is there any way of quietening the exhaust down??
I heard that putting a series of small holes in the exhaust will quieten it down??
