how much longer is the LS downpipe over the Gsr downpipe?

 

more specifically, what is the length difference from a jdm dc 4-1 over a U.S. stock gsr header? thanks i need to know how much to cut my test pipe to make it fit

 

depends on whether your gsr's o2 is in the header or the cat. Mine was the shorter header so I had the muffler shop add about 2 inches to my exhaust to make it fir. So if you're changing to a jdm dc header, you might have to cut about 2 inches or so.