In all my years of racing I tried back to back sets without bubble balancing them and will never do it again. I honestly didn't feel anything going down the track but even though I lock tite about every bolt on my race car I had bolts getting loose that never did before and have not again since I went back to balancing them.

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time