bdickey058 Posted July 17, 2009 Share Posted July 17, 2009 so i've been looking at downpipes and i keep running across these downpipes that say rear section and or front section. what does this mean? i just want a full length downpipe! Link to comment Share on other sites More sharing options...
mightyS Posted July 17, 2009 Share Posted July 17, 2009 The stock dp is in 2 parts. The upper connects to the turbo and has 1 cat. The lower dp is horizontal and connects from the upper dp to the mid pipe. The stock one also has another cat in it. I've seen the Perrin dp that has 2 sections like the stock. Cobb's dp is 1 longer pipe that connects from the turbo to the mid pipe. There is 1 cat in the lower section near were it connects to the mid pipe. Plus it fits exactly to the stock mid without needing a 3 in to 2.5 in adaptor. Link to comment Share on other sites More sharing options...
tcoope13 Posted July 19, 2009 Share Posted July 19, 2009 The stock dp is in 2 parts. The upper connects to the turbo and has 1 cat. The lower dp is horizontal and connects from the upper dp to the mid pipe. The stock one also has another cat in it. I've seen the Perrin dp that has 2 sections like the stock. Cobb's dp is 1 longer pipe that connects from the turbo to the mid pipe. There is 1 cat in the lower section near were it connects to the mid pipe. Plus it fits exactly to the stock mid without needing a 3 in to 2.5 in adaptor. So what is an "up" pipe, is that to top section of the down pipe? What part of the exhaust is the most restrictive and needs replacing? Link to comment Share on other sites More sharing options...
fonts Posted July 19, 2009 Share Posted July 19, 2009 The UP is a pre turbo pipe that runs from the exhaust manifold to the hotside of the turbo. The logic of replacing it is to prevent the cat from breaking up and getting sucked into the turbo. An aftermarket UP will also help with turbo spool a little. The install is a bit of a bitch and lots of members get exhaust leaks after installing. Most replace it for the protection of going catless. The most restrictive part of the exhaust is the first portion of the DP. That's why some companies will do a "shorty" DP that just replaces the first section as described by the OP. A shorty DP would eliminate the first post turbo cat yet still leave 1 cat in the DP at the "rear" section. A one piece DP like Cobb, Invidia replace the entire DP like mentioned by mightyS. If you get their catted DP they have one high flow cat in approximately the area where the second cat is on the rear section of the stock DP. Link to comment Share on other sites More sharing options...
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