ET difference from 3.91s to 3.54s

A welded in 6 point roll bar is close to 75-80 lbs alone. And the dana is another 60 lbs over the 8-3/4.
Yeah I really need to weigh it in its current state. No carpet saved me 35 lbs? But roll bar added ??? And I've seen lots of different opinions on weight difference between the 8 3/4 and the Dana 60.

The reason for the roll bar and Dana is that I'm putting on a Procharger in a few weeks to shoot for mid 10'secind 1/4 mile times