On 2000-2001 VTR1000-SPW that Colin Edwards rode, he complained the frame was too stiff and not allowing the rear tire to hook up properly.
They removed the upper rear engine bolt and made cuts in the swingarm for added longitudinal flex.
The 2002 VTR1000-SPW had these designed flex changes incorporated into the re-design.
Which why Edwards always preferred the 2002 bike over the earlier ones.
It put the power down so much better.
The SP1 and SP2 that we mere mortals ride is only a passing resemblance to the factory bike Edwards rode.
I would suggest leaving the engine mount bolts alone.
The SP1 suspension was more progressive than the SP2's, which had a revised link ratio.
One improvement to the SP1 rear suspension is to replace the OEM lower rocker link with the Kyle Racing link.
This changes the link ratio to a more linear rate over the OEM progressive rate.
It also raises the rear ride height a few millimeters to quicken the steering response by steepening the rake slightly and thereby reducing trail a bit.