Wotcha and welcome,
As you are not increasing the capacity of the engine or how much gas and air will be flowing through it to a huge degree by changing the exhaust I would follow Matts advice, get a good high flow panel filter, Cosworth, K&N, Pipercross, etc - an oil free one would be best as to not screw up your MAF.
If you would like to mod further look at brakes and handling packages or loosing weight that way you make the most of power to weight ratio