I finally blew out one of the stock KO3s on my 2000 2.7t. My main concern is just to get the car running again as reliable as possible, without breaking the bank more than I am.

Will I be fine with using the KO4 VAST or ECS kits w/o any fuel changes? According to both ECS and an FAQ on Audiworld, I can, but I wanted to get more opinions.

 

Send Prince at VAST an email, he is a really helpfull guy. He should be able to give you any info you need. Sorry, dont know that much about what stock systems can support on the 2.7. Best of luck!
BTW, if you are really interested in outside opinions, try in the S section. I think there are more people with K04 experience in S4s than in A6s.