When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I believe what you are seeing are the pieces that come with long tube headers. You usually have a choice on the diameter of the X pipe, 2 and 1/2 or 3 inch. The stock over axle pipes are 2 and 1/2. So when you get headers with a 3" X pipe, and want to use your stock axle back exhaust, the pipes in that picture between the X pipe and axle back step down from 3 to 2 and 1/2".
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Looks like our LG Super Pro headers.
Stock cars are 2.5" from the manifolds to the mufflers throughout. Z06 cars and ZR1's are 3" all the way.
Our Street Series are 3" collector and then go down to 2.5" just like stock, our Super Pro's are a full 3" until that piece you see there were you can mate it to the stock mufflers, or if you have a Z06 style exhaust we can supply you with the larger 3" for a full 3" system.