I mapped mine for a bit more poke...then I wanted a little more so fitted a new back box and have a de cat downpipe on order. I lowered it for looks just changing the springs then realised that when I am having a bit of fun I need stiffer shocks as it will either rub or bounce.
I am not a boy racer either, that doesn't mean I can have a bit of fun!
Mapping improves performance without putting a strain on the engine and increasing fuel consumption. Go with a well known firm, I always use AMD in Essex but there are lots of good firms, all will be slightly different and make your car perform better.
As I said, get shocks and springs, buy a good brand, get someone good to fit.
What more can I tell you?