Best Way to Add LSD to Sport Auto Model..

[zeroptzero]

I'm finding wheel spin on my Sport model to possibly be an issue in the future, I think it really needs an LSD. I am not sure if I should do an aftermarket unit or go with a factory unit from the Performance model. My dealer gave me a crazy price for an OEM unit (brand new) but it would be an easy swap. Any advice on which direction to go ? Thanks for any replies.