Originally Posted by ericschlaifer

I've been running the XB4's since the '13 was released. Great platform! my advice to you is if you are going to run the center diff at Rainman's use the 1,000,000 diff fluid. Anything else and you're just spinning the front tires and losing forward momentum. I tried 500k at HRH (outdoor wet track) and felt it was a bit soft, but still driveable. But, IMO with a 13.5 you should not be using the center diff at all on medium/high bite tracks. Just robbing power that you need with such a small motor. If you ever make it out to SCVRC, I can help you tune the car in. We also stock just about any part you can think of for the car, so it may be worth the trip for you. If you know Andrew maybe you can ride out with him. He comes out from time to time.