i was unsure in buying just stage 1 but because i already have an after market pulley from smooth flow pulleys i went with stg 1 im glad i did because the tunes between stg 1 and 2 are the same i read through my install manual and it goes on to stg2 install and it says you need stg 1 and re program before doing stg 2 which include smaller pulley and belt ill be installing this monday along with my 2.8 pulley and smaller belt which i cant wait my dealer is not open for service on weekends so i have to wait i still need to drive it. so what im saying is its cheaper to buy stg1 and get a smaller pulley than what comes with stg2 and get your smaller belt from the dealer and its alot cheaper same tune no difference just a little info thanks