Adjustable means you can go lower, really low, or scrub down low
Adjustable are the best
Why?
Lets say you get lowered springs/shocks/dampers that are non adjustable and install them in your car
And realise that your car is too low and you cannot go over speed humps/curbs without your chassis (bottom of the car) hitting unmovable objects
You cannot 'adjust' them or raise them, because you cannot - so you wasted $300-500 dollar
Now with adjustable you can set any height you want
From stock - yes stock height
To really low, or just lowered a couple of inches
See what we are getting at here?
And exhaust means the down piping from the engine, all the way to the back of the car
Exhaust is the whole system
Comprised of the headers/extractors
To the down pipe
To the catback - which is a Catalytic Converter. It catches all the nasty gas from the engine and 'converts' the gas to less harmful fumes
To a straight pipe/silencer
To a muffler - which muffles the noise, as a car without all this system is VERY VERY LOUD
To the exhaust pipe tips
Hope the picture helps
http://www.kwik-fit.com/assets/jpg/g...work_large.jpg