i might be able to offer some insight as to why they did this. i just got my vhr car a month ago and have yet to mess with tuning it, but i have extensive r&d/tuning experience with a radical revup combination that i developed outside the light of the public forums. i tune this car myself using an aem infinity standalone ecu. the car uses a large single ported 87mm gm throttle body (along with a custom intake manifold that i also built) which brings its inlet airflow cross-sectional area on par with that of the hr and vhr. prior to this i attempted to make this work on the stock ecu and found the limits of the system, as well as experienced a lot of the frustrations you guys have been going through with this, minus the vvel connection. it becomes apparent after messing with it for a while that what uprev supplies you as a throttle map doesnt exactly directly control the throttle like you wish it would. in fact that map literally does nothing anytime the ecu sees that the engine is operating within the idle range. that said, what everyone always wants with regards to throttle control is what the standalones provide... a throttle position vs pedal position/rpm map. now, given that i have been able to experiment with a comparable amount of inlet airflow (potential) as the hr/vhr cars, but with the ability to control the throttle in this fashion, i can see why the power delivery is designed to be s-shaped. i was able to set the throttle table up, relative to pedal position, in a completely linear fashion with the aem. what might not be readily apparent is that the engine doesnt necessarily increase its airflow potential relative to throttle position. so, what you find with a big 87, or a pair of 60's, with a truly linear throttle curve is that it is way, way, way too responsive at low throttle angles to the point that it makes low speed maneuvering jerky and awkward, while shifting becomes annoying, uncontrollable and unpredictable. i have a triple carbon disc clutch that without the rjm bracket is more or less an on/off switch. the bracket allows you to slip the clutch effectively enough for the car to drive and shift closer to that of a stockish car. well, that all goes out the window if the engine response is ultra sensitive at low throttle angles. what i did to fix this was dampen the throttle response, relative to sub-50% pedal position below 4k. the map is setup such that the x-axis is rpm and the y-axis is pedal percentage... while the map content is throttle position. with my gearing/tire combination all cruising and general commuting is done under 4k, so this works out very well. i rev to 8k, with the real meat of powerband beginning a little after 5k. throttle response is practically instantaneous on my setup. its very easy to get into the powerband when you want to. this way, any time you are more than 50% into the pedal, regardless of rpm, the car acts as if it has a cable throttle control... yet it is predictable at low throttle angles and rpms and easy to move slowly and shift. i sold my uprev cable prior to buying my aem, not knowing i would have a vhr car in another few months. i plan on buying uprev again and experimenting with this very sort of thing (although im "supposed to be leaving the car alone"). hopefully, once i can tune this new car/engine and gain some experience with this new cam timing/throttle control arrangement i can be more helpful. great job so far guys, this thread made a very interesting read!
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