day or so late to chip in, but if anything the cat will be the restriction point, a 3" exhaust will flow well over 600hp on a supercharged 4 litre, so it will not be an issue, and hasn't in the past on a 2l motor..
ditch the cat all together and you'll free the system up..
__________________
Jesus Built my car, Its a love affair, Mainly Jesus and my hotrod
|