It depends on the cold air kit. Most need a tune.
Throw the throttle body spacer away. What do you think that will do for you?
Its just a worthless piece of junk.
Powerhouse makes a great 4" shaft for the S197. I have had one for over two years and never had a vibration. Installation was 30 minutes. You dont need to change pinion angles unless your car is lowered. I run stock control arms still and have no problems with vibration.