Early shift might've helped you. Here's the HP/torque curve for a 2008 LX. From https://www.automobile-catalog.com/curve/2008/1429145/lexus_lx_570.html:Wow, I shoulda listened to @CharlieS
Last run, got her going pretty good, making the 2-3 shift, when suddenly BANG something in the tranny let go. Total loss of power, engine hits the limiter. Then the engine started knocking REALLY bad. Oh man... big cloud of blue smoke. I think at this point the driveshaft fell off the back of the transfer, cause it pogo'd the truck over, I think I rolled 3 times. Geez those airbags make a loud noise when they go off.... phone got tossed out and crushed, so no photos, sorry.
Actually none of that happened. Truck is totally fine, just a thin layer of oil and schmoo all over the tailgate that the tires kicked up.
First run, TRAC off, PWR on, trans in D, I rev'd up to about 2000 rpm, standing on the brakes, then let her rip at the green, never lifted. I'm #962.
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Second run, same settings, except this time I started in S2 and manually shifted. I wasn't very smooth at it, shifted kinda early.
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Third run, same thing, but I was better at shifting. I really didn't like how it reacted, it was taking too long to shift. Maybe it knew better than I did? Anyway, not as good.
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This truck is a pig, that's all there is to it. Too much weight. I gassed up on Sunday night, and stupidly forgot about tonight and filled the tank with 87 regular. More weight.
But we had a BLAST. Lots of cars, all types, even some drag bikes. I know there's video, but I don't have it yet. Will post if I can.
Sorry wish I'd found this sooner for you. Basically you just want to shift to the next gear when the next gear would make more HP than the gear you're currently in. If you trust the above graph then you always want to hit redline. But if the above isn't the real output of your motor, you could be better off shifting early if the RPMs for the next gear will put out more HP than you're getting in the current gear. (OTOH if the above is real you always want to hit redline since even the 3->4 shift would go from 5800 RPMs to ~4300 RPMs and the above clearly shows you're making more HP at the top end than at 4300.
That said I think the above is measured at the flywheel, not at the wheels, so if the HP curve at the wheels does not match the flywheel curve then the shift points change. Note that I don't actually care how much HP you are really making, I only care that the curve of the graph matches the RPM points. Also obviously I have no idea if the above is accurate.