Panda 100hp Buying Guide

The best things you can do is to refresh the suspension joints and bushes with oe spec replacements. The 100hp is pretty hard on suspension so they wear out quite readily. The oe shocks are pretty poor, Bilstein B6 are a firm favorite and really transform the ride quality.
The front suspension setup it already pretty tight so things like Polly bushes, strut braces and the like aren't cost effective upgrade. However, the DNA rear torsion bar is a relatively inexpensive upgrade which makes for a discernible improvement.
Tyres can make a big difference too but are very subjective, I love the oe Goodyear Eagle F1 myself but others have found positive results with other brands and models. F1's offer prodigious grip in the dry and good consistent predictable grip in the wet. IMHO I don't think you can beat them on a 100hp.
Fiat locked the ecu down pretty tight so remapping isn’t an option or at very least not an inexpensive and straightforward one.