Jimbo also installs an exhaust gas temperature gauge and adjusts the injector pump fuel limit.
He put spares on the front in order to use fifth gear and reached a higher top speed, but the car was slower overall, although it was still slow once he restored the correct tires, so clearly he needs to figure out what else is going on with an engine with 8 hours of run time.
I templated his car:
How high resolution should your picture be when you do this?
That car is 52.2" tall and it is 175 pixels tall in that picture, so so each pixel is .3". The template indicates the back of the spoiler is 4.176" too low, but it could be between 3.876" and 4.476"