This concept allowed us to create a long tube header design to fit all models. For the SRT8 and the 2005-2008 5.7L with Square Port heads, we went a few steps further by offering our systems with various primary sizes, (1-3/4"', 1-7/8" and 2") to fit applications from stock to well over 1000 RWHP. When necessary, we will also custom size our merge collectors.