Are the tyres a lower side wall profile than recommended for the jazz on that diameter of wheel ?
Lowering is a personal preference but I wouldnt do it if its just to make the wrong size tyres look better.
There are various wheel size/tyre calculator web sites that give accurate overall wheel/tyre diameters etc. By using these and maybe very accurate use of photoshopping you might be able to create virtual' before and after' images of your car before spending any cash.
I cant help with intake. Maybe the modifications some make are not actually making the hoped for significant difference to actual performance and tuning.
Or they are tolerant of any downsides.