I was just curious as to how the turbo works exactly. I don't mean the principle of how turbos work, but rather when does it kick in on the A4, is it a certain rpm? or when you give it a lot of gas quickly? i find it is always very responsive when at high speeds in fifth gear, which makes for a fun highway experience lol. but sometimes i feel like it should kick on in lower gears when i need a little more umph. is it possible it needs to be cleaned? id think not considering it works well in fifth. thanks

 

It is based on exhaust flow and in lower gears your engine has less load so it actually makes less exhaust gas to spin the turbo.