Sorry, we have enough data to convince me that 1.62 Max Power and 1.62 Long Tube are close on power, so close that I suggest the question of which is 'better' is more a question of other factors at this point, not the numbers. To put this another way, I am not convinced there is enough difference on mere numbers to make it interesting enough for me to spend time and money to resolve that question at this point. We have hundreds of projects clamoring for my attention, every month we need to prioritize and we try to focus always on where our time and resources can have the biggest impact.
Not clear to me what you are asking with 'what was your motivation to call the 1.62 alive' since it is available now, and it sells well every week. The motivation was clear and has been explained many times, we made it because the data made it clear the 1.5 PPE was just a bit too small with result the top end was slightly choked compared to our Max Power Header. That data was clear for a LONG TIME, Jay made that result more easy to read for the masses at Miata.net but it was not a surprise to anybody actually paying attention to all the individual results streaming out from customers everywhere. The 1.5 inch PPE only continues in production because there is one Tuner out there we don't need to name, and that guy told the masses over and over at Miata.net that the 1.5 long tube was the best and only way to go for every application, yet he never had any data to support that claim and somehow the fact that he only had that ONE header option to sell didn't make the Lemmings suspicious of his BS claims. Anybody can do their own testing as they like, including the Tuners like Jay and Mike who who can be trusted to post honest results. We have posted plenty of data here but I encourage folks to do their own testing.
I am convinced that other factors you should consider will affect your daily enjoyment much more than the answer to the question you are so focused on now. Ignoring for a moment that one choice has lifetime warranty and that same choice is also much easier to install, I suggest the comparison on SOUND QUALITY is now the decisive factor in your daily driving joy between those two choices. The RoadsterSport Helmholtz midpipe has changed the game. But don't believe me, READ the reports at Miata.net on the Helmholtz midpipe and you will quickly see that the few early customers reporting success and HAPPINESS with the results are quickly becoming a chorus of happy customers all saying the same thing...but are you listening to them?
Given everything else we have here waiting for testing time the only NC header testing I am interested to do next, that I 'may' do next as time permits, is comparison of 1.8 size PPE prototype with 1.8 shorty header on something well beyond a normally aspirated 2.0, either our 2.5 Project Blue or our supercharged 2.0. But which one? We are already OVER 300 hp at the wheels with Max Power header in original 1.62 size, there were plenty at Miata.net claiming that result was IMPOSSIBLE with MP62 and 1.62 inch shorty before it happened. Perhaps 1.8 PPE or 1.8 Shorty can do even more, I wonder how much more? The comparison would have happened about a year ago on normally aspirated 2.5 liter 'Project Blue' but we lost a motor on that 2.5 to overheating and cooling upgrades suddenly and understandably captured my attention because I suddenly realized that all the available NC cooling choices were not enough for the next phase of NC power exploration and development.
Thus, on the supercharged car I was more interested in this last year in upgrades to cooling. We spent many months on development of oil cooler upgrade (coming to the site 2016), adding our NC Singular hood vents (on site now), new NC triple pass radiator (also coming to the site early 2016), and upgrade to MP62 Supercharger heat exchanger (look for several options coming to site soon on this in early 2016). Result of all these upgrades 308 hp at the wheels....with our nearly 8 year old install of supercharger on our 2.0 2007 with original 1.6 inch Max Power Header. Thus, obviously the current Max Power Header already flows more power than most will ever get close to making!