I have a 2000 A4 1.8t with the stock boost controller I was wondering what would be a good Boost controller to buy to replace the stock one I intend on puting a K04 in and chipping the engine.

 

For a small stock turbo a good bleed valve would be smoother than a ball and spring controller. I have a turboXS hp boost controller that has both adjustments and you can fine tune it easily and i have never had any boost spikes over the set boost level.