Grimmspeed HiFlow Up-Pipe Ceramic-Coated - Subaru WRX/STI/FXT (EJ20/EJ25)Adding an aftermarket Up Pipe is one of the first things you should do to your Subaru. Arguably one of the best $ HP ratios. Our goal was to make a premium heavy duty Up Pipe for our customers! The entire Up Pipe is made of 304 SS(flanges, flex, tubing) and has a pipe wall thickness of 14 Gauge, this is the most "heavy duty" pipe you will find. Many other pipes use cheap thin steel and are marketed as "super light weight", not us. The inlet size is 1.