You may or may not need limited slip friction modifier additive depending on what gear oil you use. I made that mistake, used Mobil 1 75w-90 as Mobil 1 gear oil is one of the best, and I added 4oz of friction modifier only to find out later that the LS on the Mobil 1 bottle means it already has it. Doh! Oh well usually too much FM isn't bad, just makes the clutch packs less grippy, mine still leaves 2 rubber patches, so I'm not complaining.