Up rated bushes all round
Accurate corner weighting of car and driver seat position (I sit in the back seat)
Accurate camber setup for optimum tyre temps
Mapping of my car for pure tourque to get me out of corners faster
BTCC cage for stiffness
Uprated brakes and race pads all round
When I tested my Clio at Cadwell there were lots of very expensive cars there and I ran rings around them much to their chargrin They expected power to be the be all and end all off of the race/fast car equation and it is not. Power = weight and weight = to slow in and out of corners, have to brake much earlier, go through tyres and pads much faster. Corner speed is where you win races not down straights. This is why F1 cars weigh 600kg! My Clio weighed 820 dry.