Well, ... unfortunately and unlike UK, Italy, Germany ... things are getting harder and harder in France ... so is our MOT
I could give you a very fast answer and say "i just come to UK" !
My other car comes from Walkers and is quite modified ... the only way to go through is basically not to declare any modififcations. If you remap your ECU and declare it they will increase your insurance premium.
For the modifications ... try to stay into the original spare parts and it can go through. However in a matter of suspensions it is a bit easier. The sensitive side is the brakes ... wheels dimensions and now exhaust systems. Luckily some controllers are aware that tuning can also bring extra safety in the vehicle.
In fact we ARE NOT a country of "CAR PASSION", nowadays the law is such you are almost considered as a terrorist just driving a sport car. Now the global warming issue is a new reason to create taxes to penalize such and such car.
This is really a shame ... imagine we are not allowed to organize a meeting between owners above 20 vehicles without declaring it to the authorities, with providing a roadbook and timing of the event !
in these circumstances ... hard to be passionate ! But still there a few "irreductibles" like Asterix & Obelix !!!