Question 1.
Remaps on turbo charged car mainly results in increased boost pressure and fuelling.
This means more more air is therefore compressed and forced into the engine. To match this more fuel is put in as well, to make sure the air/fuel ratio is such that it produces a bigger bang than in standard mode.
bigger bang = more power/torque = more fun = happier drivers!
Question 2.
many people watch the water temp gauge to get to 90 degrees before giving it some welly.
however, what u REALLY want to see (and u can't unless u have another gauge) is the oil temperature.
water heats up faster than oil does. so even when the water temp gauge hits 90 degrees, oil temp may not be. oil helps all the metal bits move efficiently with minimal friction. oil also goes to the turbine shaft on the turbo....and giving it some welly and running full boost when oil hasn't warmed up can reduce the life of the turbo significantly.
in any case, wait for TT to come along to explain
