New fmic, cai, 3inch cat-less dp, car is stumbling and surging boost?
 

Audi TT 180 2001 stock tune Recently installed the cx racing fmic, injen cold air intake, and a 3 inch cat less down pipe. My car has been running choppy and not so smooth ever since. Seems like I have choppy boost and it's not smoth through the throttle range. Also was hard to start at first. Anyone have any ideas of what it could be? I have the stock diverter valve on now but I do have a forge 008 waiting to be put in. No clue what spring to run. Anyone have any suggestions or help on what Spring color to run in the dv? Thanks for your input.

Sounds like you have false air coming in somewhere. Also, Make a boost leak tester, that way you can make sure everything is sealed. I made one for a couple bucks out of stuff found at a hardware store. There is an awesome youtube video for boost leak tester with some Australian guys.