And by pulsing, I suppose do you mean a noticeable difference in say gradual acceleration or are you talking about a pulsing sound? I've had both, and they are very different, and yes spark plugs fixed the former, while the later is more related to what's often called turbo surge. If it's turbo surge, you can tell via the cluster (either via watching the boost gauge in the main screen or changing the top right gauge from tranny temp to boost). Turbo surge I still haven't fixed and often experiences during slight acceleration while at speed, my tuners have helped reduce it some but I will say, I really only noticed this after both turbo's were replaced due to the wastegate rattle issues (which dam-it, those are back).