How does posi traction increase performance exactly? I'm debating on having it installed in my 72 Cutlass while it's at the shop and just want a little more detain before I give the go ahead. I'm looking to get the best power performance out of my car as possible...

 

No performance increase per say, posi will just allow both wheels to have power to them VS an open differential which only powers the wheel w the least resistance.

 

you'll have two tires giving you traction instead of one. Depending on the unit and the way the posi is set up you can get a huge increase in performance if set up correctly. they can turn you knuckles white in the rain though when it decides to apply more power. If you plan on going to the track a lot I'd go with a posi. Mines fully locked and it binds up more then I want it to in tight corners on small roads. I wish I went with a posi in the long run. maybe next year

 

Posi (Olds marketed it as anti-spin) does not add performance per-se, but helps keep both wheels engaged so you do not have the one wheel "sit and spin" common with open diffs. Assume you would also get a lower gear ratio (higher number) than stock along with the posi which definitely helps off the line performance. Trade off for the added fun is higher rpms and thus lower mpg on the highway. A 3:42 will spin around 3000 rpms at 65-70mph unless you have a modern OD transmission.