Are there major differences between.......

One big difference with the 2005 and 2006 Boxster was the use of different airbag technology. In my 2006 the passanger airbag will automatically turn off if the person sitting there is is less than a certain weight (I think < 100 pounds). This is great if you have young children. You should still use the proper child seat or booster seat, but you don't need Porsche's super expensive airbag deactivation kit. I think this saved me about $1,000 in labor & parts.