After owning the 240z for several years, I [finally] upgraded the fuel model needles from the M58 smogger needles to the original N27 needles. At the same time I purchased a set of K&N filters and mini-velocity stacks. The car does pull harder now when I accelerate and overall I'm happy with the results.
I did need to re-route my valve cover breather to a mini filter that hangs down below, and I also added a barb to connect the breather for the fuel vapor line. The SU Carb breather hoses are still connected and are positioned "down" in case the floats ever get stuck.
