No, I live to far from the dealer. Not buying a new McLarens any time soon.

Your results are anecdotal. His Spider weighs more and slightly worse drag and maybe has worn tires or a worse road, etc. 

Good 12C/570S trap speed is 134-135mph.
Good 650S trap speed is 137+
Good 675LT trap speed is 139+

Here's his post. He has 103 octane because he was low on fuel. No difference. The car was practically new and he already sold it for a 650S. 
 

I tried to update the thread title from the Atco thread, but can't figure out how to do it. So -

Had a great couple of hours at Atco today. Managed a best of 10.275 @ 135.21 on a 1.672 60' time. Backed it up with a 10.422 @ 135.4 on a 1.789 60' footer and a couple of 10.5's and 10.6's.

I had a hard time launching during the morning. Dropped my rears down to 29 psi, which did not seem to help. Added $20 worth of 103 octane because the tank was running low. Still, no real improvement.

Then one of the track attendants told me that I needed to do something to get all the pebbles off my tires and asked me to launch in the burnout box like I normally launch the car. Did a launch control burst on the concrete pad and managed to clean and heat up the tires nicely. Then my launches were much better. Dropped my 60's by 2 to 3 tenths. Huge improvement.

Have to say that I went there thinking that I would be disappointed with low 11's because I know that it can't launch hard without AWD or drag radials. Was just hoping to get one run that topped my 991 Turbo's 10.86 @ 128 mph. Boy, did the car acquit itself well.

Everyone - and I mean everyone - at the rental was amazed. Great car enthusiasts with all different cars just loving what this thing did out of the box.