I accept that ECU tuning is the only option wrt getting max gains from your mods. But most people are looking for bolt-ons which will give good gains without the pain of the piggy back ECU and a tuning session on a dyno.
So if plenum mods are NOT dialled out by the ECU, as you believe Adam, then can anyone explain why? What's the fundamental difference between that and e.g. a popcharger, wrt how the ECU responds?
3fiddyZ, I'm never sure whether to rely on the so called butt-dyno. The fact that you've spent a few hundred on a mod may influence your opinion on any perceived improvements. Placebo mods. And even if you do feel improvement initially, maybe they are temporary and just fade away gradually and imperceptibly as the ECU slowly adjusts? Did you do your dyno test immediately after fitting the K&N and plenum spacer and did you dyno before the mods were fitted to get a measure of genuine gains, or are you referencing "stock" as per the Nissan figures?