What Nenad said. This has been beaten worse than any dead horse.Nenad said:Good advice, go to search button and ask for "Colorado air box mod".
What you did is basicly lost all air pressure that was made by car moving forward.
Second, you are now sucking ALL hot air, (produced by: engine,turbo,exhaust, and air passed through cooler) instead "normal" fresh air from outside of car. Tests of of ClubB5 member Geri (Austria) with K&N cone filter installed on V6 B5 showed 15 degrees of C higher temps compared to fully stock airbox.
Good rule of thumb says that with each 3-4 degrees of C you will gain/loose(depends on raising or lowering temps) 1% of power. If we presume that your T-car is producing same heat like NA V6 (and your T-car produces more temps cause of turbo) 15 degrees of C higher than stock, will bring you down for 4-5% in power.
Simply put, for the most part, you take a step backwards removing the stock intake. Modifying the stock intake has helped a lot, as you still retain the intake of cooler outside air, and the slight over pressure from the car's forward movement.
Hope this works for you, but a lot of experience has shown that you want to keep the stock intake, and maybe just reduce a few restrictions in it.
Some of the guys here say their cone setups (removing or opening up the stock intake) are better, but I don't know. A lot of guys with the cone intakes have actually built heatshields to compensate for the "openess" of the design, and since learned that when it was all said and done, they more or less rebuilt a stock type intake system.
Doing the Minnesota and Colorado mods on a stock airbox work better than we expected. Even the stock airboxes are working good with heavily modified and chipped cars.
The key is to pull in as much outside air as you can to improve the airflow (turbo lag, high end breathing, etc.), without increasing the percentage of preheated air.