read through this 1 and there is another good 1 started by DJ Speil
https://www.audiforums.com/m_434978/.../tm.htm#434978

 

The Kit you are looking at is a ATP Turbo kit website www.atpturbo.com they sell one of the best turbo up grades on the market check out the website they have dino sheets showing 300 to 380 HP with this same kit. The fastest A4 in the world runs a garett turbo from ATP 10.82 Second 1/4 mile 500+ HP this is a lagit turbo upgrade,