Originally Posted by Brillo

Tim,

Is the stock ECU sophisticated enough to compensate for a different turbo without a retune? Its seems to compensate for manual boost controllers up to a point. How is it adjusting the AFRs as it doesn't have a wideband? Is it using the knock sensor to keep everything in line?

Of course a proper tune is going to get you the most power and efficiency, but it seems like some folks are content to just upgrade the turbo and exhaust and leave the stock ECU alone which kinda concerns me.