About AR Design

AR design creates and sells some of the finest products available for your performance vehicle. Specializing in exhaust components mainly downpipes for the newer turbo BMW motors.


The only 4" Catless Downpipe On The Market

The only 4″ catless downpipe currently on the market! Built with a carefully made 4″ to dual 2.5″ collector that mates to the factory style exhaust.

Key Features

  • Typical gains with tuning in the 20+hp range!
  • 100% hand crafted in the USA from premium 304 Stainless Steel – flanges and O2 bungs included!
  • Water-jet cut 304 Stainless cat-back flanges, and CNC’d 304 Stainless V-Band flange.
  • 100% TIG welded, argon back-purged.
  • Set of our exclusive bomb-proof exhaust gaskets included.
  • Grade 10.9 Metric Hardware (145,000PSI tensile strength, C32-C39 Rockwell, Zinc Plated), and Nord-Lock positive locking re-usable washers included.
  • Factory location O2 bungs, with an added bung for a wideband O2 sensor!
  • Available with a 2000°F ceramic coating. Coatings come with a 3 year warranty against corrosion and rust to original owner.
  • Lifetime warranty against any manufacturing defects given to original owner.