hmm. you seem to be doing a lot of things that are working in opposition to each other, like increasing input trim and master volume trim, turning the boost switch on and at the same time running gain at zero and turning the bright switch off. remember that the amps in the axe are models of real amps and behave exactly like real amps. nowhere in any universe would i run a jumped plexi with both gains at zero and then slam the input!
your patch had way too much gain and had lost a lot of the characteristics that make plexis so loved. no thump or swirl...gritty, rather than sizzly and frankly a bit weird.
i turned off the boost, reset input trim and master volume trim, put the gains and tone pots at a sensible level and turned bright back on. i replaced the drive with the 808 with more sensible settings and bypassed the eq. i also turned the variac back to default.
the amp is now "speaking" better, sounds good on the neck pickup as well as the bridge and will respond to playing dynamics!
so many extremes in your patch (most of them working against each other), i would say try not to do anything you're habitually doing and leave the advanced parameters alone. stay simple. the tones are in there and they're available from the basic controls. you wouldn't buy an amp and then immediately take the lid off and start messing around with the components...!