Update: replaced the old Weber IDA velocity stacks with a newer design from JPM. These are their Raptor stacks that create a smoother entry for the air flow, and also add a few cfm.
The Raptor stacks must have helped as the Beetle ran 0.16 seconds quicker and 3 MPH faster at Castrol on Friday. This was my first 12.6-second ET at Castrol, as I've only ever achieved that once before at Mission Raceway (sea level):