To Service pre-sale or not?

[OldChap]

I'm after some advice, please. I bought my 981S Boxster when it was just over a year old, from a Porsche Main Dealer, and have now owned it for over 10 enjoyable years, and 82,000 miles (I normally change every couple of years, but it's a great car). I'm now selling it and wonder should I sell it as it stands, or as it's been regularly serviced at a main dealer and has the extended warranty, should I pre-sale, have it serviced again, this time the 12 year service, at a cost of £1892, plus extend the warranty, which will be another £1200. My dilemma is, will I recoup the £3000 I've spent in the resale price?

[OldChap]

Thanks for the advice; I'll go with the common consensus and advertise it in a couple of weeks as it stands. My price for the warranty is clearly out of date, another reason not to renew.