I was commenting on the other guys post,
sorry I'll be more constructive for you
in my opinion it's a big undertaking to remove the nismo spoiler and should only be done properly, no shortcuts.
There will a total of 7 bolt holes on each rear quarter which will need to be patched up, if you are going for the wingless look the 4 bolt holes on the boot will have to be filled in as well, if you want to add a spoiler than don't worry
that still leaves the 14 bolt holes which will need to be patched up for the rear quarters.
welding plates behind and bogging the holes will be cheaper but rust can still happen and the rear quarters can warp if a rush job is done so paying the little bit extra for a proper job will be better for the long run (ie; the panel shop should solder the holes up, not weld plates in and bog, blend paint from the roof back etc so it was as if the car never left the factory with that ghastly spoiler)