Your fine. The long tubes and motor mount with tune aren’t going to cause this. The headers are not part of the engine balance. This engine in the tear down has been exclusive use on track at constant high rpm with a non oem balancer. Jury is still out on that. Don’t equate what you read here to ”my motor is going to grenade if I put a tune or long tubes on it”. The tune is just tweaking fuel/air ratios, timing advance, etc to make the most power with given components. The motor in this thread was in no way killed due to tuning. No detonation. Tune was fine. Power he was making wasn’t pushing it be any means. If anything, the tune was conservative with just 500 at the wheels on E85 and with long tubes. 510-520 at the wheels is pretty common with E85 and long tubes. Don’t mess with the internals, flywheel or dampener. Those will impact the motor balance and vibrations.This thread has me freaking out now. I just put long tubes, Borla cat backs and BMR poly motor mounts on my car, not to mention the flex fuel tune from PBD.