surely the point in buying one was for the warranty.
Larger turbo and more power could have been achieved much cheaper.
Id stick with what you have and enjoy the piece of mind you get with your warranty.
Learning to drive it to its limits should be first on your list. Get some rally/track tution.
You want bigger than 500 mate its got to be stroked. This brings the lag right down. In fact if I were mitsi I would of stroked the 400 as standard in the first place (then you wouldnt of seen it get beaten by A hyundia or whatever). 2 ltre sucks.