When Acura got a GT3 Porsche back from the dealership while using it to help develop the NSX’s steering, they found a note under the hood... "Good luck Honda"

Per common practice, when Acura bought a 911 GT3 for its test fleet, it did so anonymously, but Porsche saw who it belonged to when the service center accessed the car’s data, according to Automotive News.

 It was at this point that Porsche decided to have a little bit of fun with its counterparts at Acura. “Good luck Honda from Porsche. See you on the other side,” read a note left under the 911 GT3’s engine cover, according to the NSX’s dynamics project leader Nick Robinson.

The NSX team also benchmarked a McLaren 12C, and although McLaren never figured out that Acura owned the particular car, the dealer in charge of servicing raised an eyebrow. “[The McLaren dealer] wanted to know ‘Where did you go 205 mph? What track?’,”

http://blog.caranddriver.com/porsche-left-a-note-for-acura-in-the-911-gt3-used-as-benchmark-for-the-nsx/