I think Tom was onto something with his improving the 172 post.
Id like to follow on from that a little.
As far as tuning a 172 goes there are a few area for improvement
1. Remove Unwanted Weight
2. Better & Lighter Wheels And Tyres
3. Uprated Suspension
4. Modify Suspension Geometry
5. Aftermarket Performance Exhaust System (A.P.E.S...lol
6. Aftermarket Airfilter or IK
7. Aftermarket ECU
8. NOS
9. Individual Throttle Bodies
Ive tried to order these in the order that most people would do the mods in.
What Im after from you lot is, in each category, what make, model of improvement, would you consider for your car if your aim was to produce a high performance 172