Rear axle spacers, in my opinion are one of the cheapest and easiest of mods which you can notice the difference.

Then i would then personally say the lower front strut brace to tie in the wishbones. Note, i think front upper and a rear strut brace are a waste of time on the Puma.

Followed by bigger front brakes, i prefer the m6 Fiesta ST 280mm front brake setup over the 300mm Mondeo brake setup.