i read that installing upgrades without the 09 tune stage kit their little performance gain since the ecm will limit performance to stock level, has anyone did major upgrades without the factory tune and what did you notice or gain performance wise was it worth it.
i know anything done is better than stock but a 3-10 hp gain how often you going to feel it, without the tune kit?

 

the way it works is the ECU limits PEAK hp, but everywhere else you will realize full gains from your mods. so you will get up to speed and power will climb faster up until peak power, at which point you will be making stock power levels. so while your peak hasn't really changed, power throughout the rest of the band will be improved.