rear wheel guards and carbon fiber shock tower ???

Just curious what the purpose is of having the rear wheel guards i see on some of the truggies and buggies
like these for instance??....http://www.amainhobbies.com/product_info.p...oducts_id/13897
also...what are the pro's and con's on using the carbon fiber front and rear shock towers??,like this...
http://www.amainhobbies.com/product_info.p...roducts_id/8701
i'd like to cut some weight on my crt x2....but are they strong enough also ?....thanks for the advise