I have seen a couple posts on stage 3 upgrading the displacment from 121 to 128. Is it reqired to upgrade the throttle bodies and heads? I am not trying to ring out every drop of power but the cost to increase the displacement (ie pistons and jugs) from S&S seems very resonable once you already unlocked the ecu and upgraded the cams. If you have to Buy new heads or port and modify the heads, it likely becomes very costly. Just wondering if anyone had thoughts on what is required. I have also reached out to s&s and krazy horse.
