Didn't notice much of a difference in power (if at all) with the 3.25". Looks schmick and sounds great. A bit loud down low, but at cruise speed and idleing, can't even notice it.
Again, the exhaust is a bit bigger than I needed, but seeing as a turbo is coming soon, I opted for too big to save money down the track.
As for the insurance, insuring it in your dad's name is a waste of time. You don't earn any no-claim bonus for yourself, the excess also makes it a waste of time and can also give the insurance company a reason for not paying out too (i.e if you insure a WRX for example in your dad's name, they will not pay if a driver crashes that is under 25!!). Same could apply to your car. I got quote just under $4500 with 0% no claim, no mods and a speeding fine just recently through just cars