My 03 S4 has just turned 40000kms. I've had a few fueling problems recently so I thought that I'd get it sorted and do that airbox lid mod I've wanted to do. The bike is stock.

So I duly presented the S4 to the local Duc shop and asked them to get a baseline dyno, fix/setup the fueling and take the tape off the airbox lid to expose the panels I opened. Then a final dyno to see the results.

Now the numbers may shock some, 98 max hp baseline and 108 hp after fueling fixes/setup. Ignoring the high sounding numbers, concentrate on the gains... 10hp.
I get about 4/5 more horses where I really wanted it @4500-6500 rpm which is close to a 10% improvement. 

Plus with the setup I've got a more balanced motor, dives better, accelerates better and doesn't stumble anymore. 

Worth thinking about isn't it?  Just don't ask how much it cost 

BTW the airbox mod produced no gains apart from some lovely noise under acceleration.

Sounds like it was worth it regardless of the price tag.   

How much did it cost?

oooo lemme guess lemme guess
I'm thinking 650-700 with PCIII

That's pretty serious gain in HP and if driveablity is better that an important benefit. 10 horse is worth a lot of $$$

I asked a well known hot rod Duc shop about setting the squish, degree cams with a good fine tune and got an estimate of something just short of $1500 bucks.

If my ship ever comes in .......

LA