I found my original was moving when trying to time it. Timing kept moving around and I couldn’t get it right. I made a mark on it and the mark would change every time I fired it up.
I used this stuff from Amazon and it made a huge difference. Make sure you seal off the trunk from the back seat as that makes even a bigger difference. I put something on both sides of the back seat mounting frame and some on the trunk floor.
Also do under your back panels and cover the...
Hemi killer I used the mass backed also and not real pleased with it. As you know it’s preformed and with the mass backing if it isn’t formed properly like mine it’s hard to get it to sit good. Mine was off on the back section at the rockers and I couldn’t get it as nice as I would have liked...