Re: to LSD or not LSD?
I'm not sure how comparable this is but I found that on my GTA an LSD reduced my lap time by a couple of seconds over a two minute lap and transformed the cars active handing.
I suspect the difference might be a little less on less powerful cars.
If you are currently spinning your inside wheel on corner exit an lsd will help hugely.
You can also feel the extra rotational help an LSD provides as the outside wheel "turns" the car.
For powerful cars LSDs also help significantly with straight line acceleration since there will be no premature wheelspin on one wheel which would immediately rob power from the other wheel which could actually use more power.
I'm not a doctor - but I really do recommend braking later