Exhaust Design

[Billy Mild]

I recently acquired a set of used SW headers. At some point the collector was changed. The standard 3" collector was removed and a 4" collector was welded on. After doing some research on reducers it appears the pickings are slim for a 4" to 3" reducer that also has a smooth transition. I would like to put the headers on myself then drive the car to an exhaust shop to have them connect it to the rest of my exhaust. The reducer is what throws a wrench in this. I would hate to use a step down reducer that would disrupt exhaust flow.

My exhaust is stock, minus center resonator being deleted, and axle back Borla installed. It sounds good and doesn't drone bad.

What would be the best thing for my overall exhaust design, change my collector on the header to the SW 3" collector, or find a good reducer?

I would like to run cats on this car. I am looking for C6Z cats right now.

[Mr Blue]

SUMMIT sells a concentric reducer by Vibrant that is a smooth transition. VPE2632

David

[RussMcB]

Burns Stainless offers some pretty good stuff.

http://www.burnsstainless.com/transitions.aspx

[Gunny]

check your measurements carefully ...

if your SW headers are long tube it "might" be a tight fit getting a 4 to 3 transition AND a cat to fit into the space.

I have SW long tubes and, at one time, had 3" round cats slipped onto the headers and shortened to allow a V connector to connect to the Borlas (resonator & muffs). I know the cats had to be shortened; don't remember if the inlet pipes to the resonator had to be shortened.

[mike100]

I would like to see a pic of that collector. It might be best if you could have it changed back to 3" if possible.

[Billy Mild]

Here is the pic:



Exhaust pics:







If I need to get some more pictures let me know. Or measurements of the headers themselves.

I think the best thing to do will be changing the collector to the normal 3".

[Gunny]

Originally Posted by mike100

..... It might be best if you could have it changed back to 3" if possible.

Originally Posted by Billy Mild

.... I think the best thing to do will be changing the collector to the normal 3".

I agree

[mike100]

Originally Posted by Billy Mild

Here is the pic:

that's interesting... I guess you might retain the 4 into 1 part and ask your local exhaust guru how to swage a pipe down to 3" by the time it gets back to the original outlet location.