2004 e500

whats up all....this is my situation i have started a new job and been saving money for a while to get a new car and for some reason with so many things i can spend 30 k i have decided to buy a 03-04 e500...my question is how modafiable are these cars???im not looking to make any big changes i would like to do intake exhaust and a tune..also a few video audio upgrade but i know that stuff real well and dont inticipate any issues..if anyone has any info and/or links for me please post...thanks jonathan