I'm huge fan of sound engine and AC need some more dynamic in its to feel the car power. When you press pedal to the floor the sound have to be louder than when you cruise.
All mods i found on internet are trying to change the samples. I don't think the problem is there. Samples quality are superbs imho but volume need to be adjust for the need. Keep in mind that this is a personal perference and I'm in anyway professionnal.
I edited Lotus Elise SC2 sfx to start (will try Ferrari 458 next). I m really happy of the result. Supercharge whinning and bodywork been tune down a lot. Dynamic have been increased all across the rev band. The little Lotus now sound hangry when she rev up. Playing with cruise and full throttle will now give you the missing sound difference AC have at first.
Hope you will enjoy.
Don't forget to backup your original Lotus SFX directory before to replace it.