Where is it legal to add ballast?

[Tom Meyer]

The requirement that the 1/2" bolts for permanent ballast be welded but the 1/2" bolts for the removable ballast can remain unwelded is probably not specifically for safety. It's probably more about honesty. And I don't think we are talking about welding the bolts so hard that they get cherry red. A little spot weld or a small amount of braze has passed tech all the time.
_Or an nice bead of silicon covered with a quick coat of paint. Just joking.

[older racer]

at end of track? woodburn?? lol

[SSDiv6]

There are two narratives to adding weight to a racer car:

1. You add or remove weight to just change classes without caring about the effect on the suspension and percentage of rise.
   
2. You add or remove weight to change classes, from specific locations, knowing how it will affect the suspension and percentage of rise.

As others stated, if you ever have an opportunity, scale the car and check the instant center and variations by placing weight for different classes at various locations and document your findings.