How much will adding 16 lb to my car affect ET/mph(rotating weight)

Cudafever said

Locomotion thanks for all of that,
adding weight is something i'm considering. What is the least expensive way to add weight.(safely) with the price of lead a lead bumper is out of the question.:D
Each tire/wheel combo weights 8 lp so it 16 total. the 32 was double weight to get translate it to car weight to us the 100 per a tenth 1.00 rule

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Well, a tenth is .10!

If I remember correctly, NHRA has rules where every 100 lbs should be bolted down with at least 2 grade 8, 1/2" bolts to the frame or solid crossmember. You can bolt ballast boxes above & into the frame rails to make it easier to add/subtract weight, bolt steel bars or plates to the frame rails or weld in crossmembers between roll bars or frame rails to bolt weight to also.
Depending on the car & bumper configuration, you may be able to add some weight around there. '74+ A-body bumpers using shock absorber brackets, for example, have some contoured braces/reinforcements inside the bumper that make a good place to bolt some weight into. People have also been known to have lead shot poured into the rear portions of roll bars and/or in added bars.

You don't have to get carried away. Adding 80 lbs to a bracket Challenger I had years ago made a big difference in consistency, especially at marginally prepared tracks.