With the short track races we host in New York, I’ve always had issues with traction on 8" kendas. Not on acceleration (I wish I had that much power), but on sharp turns.
I picked up a set of Newbee rims because I wanted to try stretching the kendas, but that ultimately didn’t give me a whole lot of extra traction either. It was noticeable, but it still felt sketchy on the really sharp turns. Strangely enough, I was only losing traction in the rear, so I tried putting the Qind 200x75 fatty tires on the back, and it has worked wonders. With a significantly larger contact patch in the rear, I was able to do full lean turns.
Since I was still using kendas in the front, I still had a very sharp turning radius and the difference was almost negligible. I was able to not worry about maintaining traction and I was only limited by the maximum lean of the trucks, which was awesome as I was able to lean very hard. I don’t know how this may change on a slick gokart track, but my experiences are on plain ol tarmac.