all i can think of is that ad is for the suckers out there. why buy a extra down pipe?
like i said the 3 short pipes are the 3 inch down pipe. take the middle part out and a cat fits in its place.
is their an O2 bung in the flanged section ? will an extension be needed ? would i want the 3inch inlet/outlet or the 2.5 ? can they be clamped instead of welded ?