I do find the stock Thunder bushings will split after a while, but the clear blue ones I have on my 149's have been fine for a while now.
But also - Thunder has an upgrade kit with better bushings, both sets of kingpin washers, kingpin nuts, axel nuts, and pivot cups for a few bucks less than one set of Bones bushings. It retails for only $12 in Canada so I'm assuming it's no more than $10 US. That's a crazy deal for what comes in the package.