[MA70-3.0GT]

Agreed, stock springs (or any springs for that matter) should not be cut as the temper of the metal can be affected by heat, as already mentioned.
Plus, and this is the one a lot of people don't consider, the spring rate (the poundage of weight required to compress a spring a certain amount) is worked out with the stress being divided between all of the coils, if you start removing 2 or 3 coils from a spring that has say 25 coils then you've effectively increased the load that has to be taken by the remaining coils by around 1/8th (12.5% or on a 1500kg car about an extra 175kg) & thus made the spring softer as well as shorter. 25 is a lot of coils to start with and the less coils that were on the original before cutting, or the more coils removed, increases this percentage considerably This increases the chances of bottoming out & also can mean that the springs are to all intents and purposes dangerously overloaded.

OK, on some less "finessed" cars you can get away with it because the working tolerances aren't so close (provided the MoT/DOT man doesn't notice), but on something that's already been tuned to give a sporty ride from the factory & potentially will be hitting 150+mph, there's not really much room for error, hence why companies make a lot of money selling uprated & lowered springs, because that's the only safe & legal way of doing the job.