You also got screwed on the price *even* if that was the fault. The MAF is anywhere between $200-$300 depending on where you buy it. It takes all of 2 minutes to remove/install. You only require a a set of security hex (central peg in the middle) drivers that I bought locally for $12.00.
9 times out of 10 the MAF is dirty and can be cleaned with a couple of shots of injector cleaner. If he was at the dealer level he used the Porsche tester which would have directed him to the MAF sensor. Dealers remove and replace - not clean and replace. It's how they make their money.
But you got killed on some bogus hourly labor rates here as with the part price, and dianostic. The labor is not more then 1 hour plus the part install - 2 at the most. So lets say the labor rate is $150 and hour and we have a slow guy who takes two hours. There's $300 plus the part cost at at an over charged $300 plus whatever are your local taxes. I figure no more (on the high side) then $700 but should be around $500 if you went to an Indy garage. But $1100.00???? They saw you coming.
You can buy a MAF for a non-Egas 996 for a s little as $215 here (
Porsche 996 & Boxster Intake System - Page 2) and you know the dealer gets this part at half this rate - so you figure out what the mark up was on your job!
I'll tell you what he'll say when you go back to him: he'll tell you it's a "new" code! They replace the MAF as the 'default' fix no matter that it can be cleaned or tested. It's a quick turn around and out the door you go with your wallet a lot lighter. A lot of the time they are right, it was the MAF - it was just dirty!! For the returns where it wasn't the MAF they will say well because the MAF was bad - that led to the O2 sensor's going bad so they have to be replaced as well. OMG the scams they play.
Same with gummy crap on the edge of the intake butterfly or in the barrel itself. A quick clean and the idle clears up and stops throwing codes - maybe a shot of injector cleaner into the idle control valve. An indy will try this first but dealers will throw in the $350 ICV and run injector clean up service and it's another $2000 rape_a_thon.
The best scam is when they find your oil fill cap is loose or the O ring is missing from the inside of it and the air is leaking through, which of course will throw a CEL if you drive long enough this way. Then it's open season on your wallet and you'll have no way to tell WHY these codes came up - they will just show you a print out of what they will say are sensors that NEED to be replaced.
Same with gas cap's that are defective or not on tight enough - another CEL. Of course it will show a fuel pressure issue - the gas cap pressure relief valve has failed open. Gas caps are $14.50 on this site. Now of course you'll be told it is a fuel pressure regulator that *needs* to be replaced... considering the labor rate to replace this part - the default setting is ALWAYS the difficult fix and expensive part.
Buy a code reader or if you have a few bucks Durometric software and cable.
Find yourself a good indy in your area - ask fellow P car owners - and then develop a good relationship with them. You'll never go back to a dealer again unless you buy new and have a warranty.