Originally Posted by Olivier_TFE
That is big difference! For reduce underteers, better bigger say bar front or rear??
I hope reducing understeers and front tires wear too, because sport or track driving with stock 135i is too much expensive for the front tires! (Mine: 5000 miles and dead!).
As Scott noted, there is lots of variables. But if you want to add more front grip to a 135i, I'd go with a bigger front bar first, and then lots of negative camber up front, really as much as you can get. The lack of front negative camber reduces grip and increases tire wear when you push the car very hard for autox and racing use since you are only using the outside of the tire.