One guy was running two NCD spacers stacked on top of eachother to clear 37's. He said it wasnt really the correct thing to do and was only temporary, but it can be done. Im not sure what else he had done, but mostly stock. Anything more than the 2.5 spacer though and i would look into a new upper arm. I think Gary at ncd has a really *****in one for only $400-450. Dont remember. The stock upper arm will make contact with the coil bucket. Also stock shocks suck. If i were going up i would buy a bolton coilover and upper arm and be done. Not too high and waaay plusher than stock