Velocity Stack
Bored MAF
Ported/polished throttle body
Cams

you did these to your audi a4 right? if you did how much did it run you and did you have someone do it for ?

 

velocity stack = ~$40
Bored MAF = ~$200+core
Throttle body = ~$300+core

I don't have cams, but the best bang for the buck is buying cams from a pre 1996 12V. The cams were more advanced than the A4's.

I bought all of my stuff from Abnormally Aspirated.

 

where is that site?

 

and what is a velocity stack i tried to look it nothing comes up

 

The site has been removed. Mance, the owner, is a retired gentleman. He was taking on so much business that he closed his website and only takes work by "invite". Basically you just have to know someone who has been a customer (me).

Inside the Mass air flow housing is a metal sampling tube that is very restrictive. He removes the tube completely and bores the diameter of the housing out as far as possible. Also inbetween the MAF housing and the airbox is a metal screen. This screen is used to smooth the air out before it hits the MAF sensor. The screen is also a retrictive point. This is where the Velocity stack comes in.

If you remove the sampling tube and the screen the volume of air will increase, but the velocity of the air will decrease. (bournellis law) Since the MAF sensor will perceive a drop in velocity it will throw a check engine light. The velocity stack is used to increase the air velocity and smooth the air out before it hits the sensor.

Hope that helps.