The stoke intake system is said to be very well engineered. It is quiet, and at the same time is very efficient in terms of airflow. It is for this reason that many people do not upgrade their airbox at all, which is not the case for cars in general. Most cars see significant performance increases, but on the B5 S4, it was made right the first time.

There are many aftermarket intakes available, however the performance gains are questionable. Most seem to believe the stock airbox performs just as well as an aftermarket system give or take about 5hp.

• Cone Style
  • AWE S-Flo
  • Evo Intake (Evolution Motorsports)
  • X-1 Intake (Custom made by some guy on the forums?)
• Drop In Filters
  • K&N
• Airbox Mods
  • Just cut a hole in bottom? of airbox
  • Cone style intake inside stock airbox (Write up w/ photos - Audiworld.com)

Comparison Threads

• Evo vs DarIntake

See B5 S4 Diverter Valve