OK, so what exactly do you mean by "bumpsteer"? If you haven't changed the steering, then you shouldn't have any bumpsteer. What exactly are you feeling that you are calling bumpsteer?
Bumpsteer is when the vehicle steers itself when you hit a bump big enough for much suspension cycling. It's caused by the drag link and panhard/track bar not being aligned well enough, so that the drag link ends up turning the wheels slightly as the suspension cycles even though the driver is holding the wheel straight. Basically what's happening is that the lower end of the drag link is traveling though a different arc than the lower end of the panhard bar, so the drag link moves relative to the panhard bar and so makes the wheels turn slightly.
If you are getting any kind of shake, shimmy, or vibration as the suspension cycles, then that's not bumpsteer.