.870 torsion bars

Mopar Performance torsion bars
340 car spec 892 / 893 number
.870 dia
Dirty but super nice shape no rust, very low use, went to /6 bars for drag racing
$100 OBO plus shipping
View attachment 1715349282
I thought I had asked this earlier, but for some reason it seems to have not posted to this thread. Question...What is the advantage of /6 torsion bars for drag racing?