they change the front valve cover gasket, thats all.
mine were leaking, so i just changed them both. whos got time to drop a car off for a hrs work, and 1/2 a job? front cover is easy, the back one a bit harder due to having to remove a few sensors and a support bar from the alt.
funny, i just got that same recall notice a few days back, this is the 3 rd one i got.
id be more concerned with the fuel line connection on the fuel rail over the supercharger. if you have a brown stain under it, its leaking.
