You wont ever see big improvements without big money! NA tuning doesnt realise an aweful lot of power. It will give you noticably more mid range punt, but that will be about it. Even with a remap you wont realise much more power. Will look good though
Yeah i am aware of that but i think these mods are a case of making the car breath better and get better through put.
You asked if you would see big improvements, I was point out that you wont. The ECU will only allow the engine to breath a certain amount more. The mix will lean out as you give it more air until it reaches a max value then it wont breath any more. So you will get the benefit of a bit more throughput, but not a lot. Most gains are had from evening up the airflow to the front cylinders and a bit of extra breathing