Is it 280 or 276 HP for 2005 S?
 

Is 2005 and on boxster S rated at 280 or 276 HP?
Some magazines rate them at 276. also 237 for the base one.

If it is 276 then the increase from 2003 and 2004 S is only 18 HP.

There are new SAE test procedures for determining horsepower that I believe came out last year. Perhaps the discrepancy is due to that?

If so, you'd have to retest the old boxsters with the new tests to get comparable numbers.

http://www.theautochannel.com/news/2005/04/11/034631.html

Porsche states 280hp and 240hp in their brochure and order guide

The 987 figures of 280, 240 were determined using the previous standard test procedures for net-horsepower, as stated in the owner's literature: SAE J 1349

http://www.sae.org/certifiedpower/brochure.pdf

You can easily pick-up this "lost" HP if you simply de-amber the side markers and remove the air bag warning stickers on the visors!! :)