The A4 is one of the first Audi's with OBDII and as such it will be
difficult to do a chip for it. The chip itself is an EEPROM and it is
soldered to the board. This means 2 things.
1) The first one is going to have to be unsoldered from the board to be
read, simply to get the base data.
2) The chip is then going to be reprogrammed and soldered back on the board
or it will be soldered back on the board and then the computer reprogrammed.
Without denigrating Dinan in any way, I doubt if they have sorted out the
link to the computer yet, but then they might have, bearing in mind their
expertise with BMW computers. Certainly, that other internationally famous
company Superflips hasn't got it sorted yet and they pull the chip and
solder it back in. But I hear they are working on the link :)
They did think of obtaining a core computer but the high cost and poor
availability outweighed the potential profit bearing in mind the small
number of potential sales at the moment.
The gain you can expect from the conversion will be about 10% in HP and
10-15% more torque. The cost of lending your car to Dinan for a week is high
compared to a $200-400 chip. Thats the way Dinan get their development cars.
One thing you can be sure of is that it is unlikely you will get a better
chip for your money elsewhere.