I am in the process of building and gathering materials for my cat stack. I am looking for a reducer to go from the 8" cat stack to the 4" exhaust systme. I know it would probably be a lot easier to upgrade to a 5" exhuast and then connect it to the stack, but I purchased a silverline muffler a few months ago that is for the 4" system and would also like to keep the cat on there, just to keep it legal.

So...anyone have any suggestions to bring 8" down to 4"? So far, I have found something like this, http://www.ventingpipe.com/index.cfm...on%20Dura-Vent
Kinda pricey, but it would get the job done in one piece...I think.
Suggestions??


ps...yes, I will post pics as I go

 

I would use a flat steel plate and weld and exhaust elbow inside the plate then bolt it to the belt floor is a good way to reduce it

 

Im a little confused. Do you mean weld a flat, steel plate to the bottom of the stack and then just cut out a 4" hole to connect?

 

The adapter you found is probably one of the few that will go from 8" to 4" and possibly work. You might be better off building a small collection box to fit in the bed to do the reduction. Maybe 9x9x3 or so. 8" hole on top for stack to fit into and 4" hole on bottom for normal 4" piping.

 

^ That is was what another guy I talked to in town said. The only other thing I have found that might work would be the reducers used for stoves. If I used those, I would have to go 8" to 6" and then 6" to 4". I am leaning towards that as a temporary solution but am nervous how it will hold up to the heat/abuse being so thin walled.

 

I agree you should just make a flat square with an 8" coupler welded to the top and a 4" pipe welded to the bottom that goes through the bed and can be hooked up to the existing exhaust. cheap and easy and will look clean!!!!