If you know you won't ever need the cage to run 9.99 or quicker and or faster than 135.00 MPH in the 1/4 then don't add the weight
If your thinking or wanting to run quicker than 9.99 and or faster than 135.00 then do everything now to make the car legal instead of having to do it later, same thing on all the safety gear in the car and for you now also