M20 exhaust with swap

[SHunter]

Who here is using an M20 exhaust with their swapped car?

I'm not looking to make a million horsepower or a bunch of noise. I'd like to make at least the 190hp of the stock m52b28 and I like the sound of the exhaust on my M20 car now. I have a no name SS catback with no resonators. By my measurements the tubing is twin 1.75" coming from a hollow cat with a 2.25" inlet. It's surprisingly quiet with only a muffler but has something to say when I get on it. The thing is, Magnaflow shows a cat with a 2.5" inlet and twin 2" out for the m20. Did the PO "upgrade" the car with a smaller exhaust??? You guys think I can make this work with some m52 headers and custom downpipe or will it be too restrictive for the slightly larger engine? I do plan to run a new cat BTW.

[scottinAZ]

bone stock, the exhaust is 1.75 inch dual from the downpipes. I am running a modified stock exhaust on my swap. I used ebay SS replica headers into modified downpipes into the stock exhaust. Ebay ss reps are a bit odd, as one header steps down to 1.75 inch already, and the other is at 2" requiring one reducer. only things I needed to source for the exhaust to work was a couple of 1.75 inch straight sections and said reducer. all bends were scavenged from the original exhaust downpipes.

[SHunter]

Hmmm...So no x-pipe for you? Or does the stock cat merge the two sides?

I was thinking about using these headers since they have dual O2 bungs and I'm going with an obd2 engine.

http://www.ebay.com/itm/BMW-E36-323i-325i-328i-M3-3-0L-3-2L-92-99-Long-Tube-Exhaust-Header-Headers-/230702990660?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item35b6f84544

I would be needing a y/x-pipe into the cat or need to find a cat that acts that way. Anybody know if the e36 dual in/out cats are separate all the way through or do they act like an x-pipe?

[jahnaboi]

What I did:

Obd2 Headers > Obd1 Midpipes (Modified with e30 flanges to accept e30 exhaust) > E30 stock exhaust. Quiet as hell.

[scottinAZ]

Hmmm...So no x-pipe for you? Or does the stock cat merge the two sides?

I was thinking about using these headers since they have dual O2 bungs and I'm going with an obd2 engine.

http://www.ebay.com/itm/BMW-E36-323i-325i-328i-M3-3-0L-3-2L-92-99-Long-Tube-Exhaust-Header-Headers-/230702990660?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item35b6f84544

I would be needing a y/x-pipe into the cat or need to find a cat that acts that way. Anybody know if the e36 dual in/out cats are separate all the way through or do they act like an x-pipe?

No X-pipe, everything merges as per the stock exhaust (not counting the dinky pipe in the downtubes that the o-2 sensor mounts in on the stock M20 exhaust)

I cut the stock exhaust about 8" forward of the cat, scavenged the bends to fit into the header collectors, and called it a day.

collector to cat bend:


View into cat:


these are the best pics I have right now, its a bit of a pain in the ass to get under the car for better pics....

[trackjunkie21]

Any vids on how it sounds? Would love to hear it!

[scottinAZ]

best I got right now

[MaxBell]

Not bad. I may even just run the stock M50 exhaust manifold for now.

[scottinAZ]

Not bad. I may even just run the stock M50 exhaust manifold for now.

as long as you have the E36 downpipes to match to the manifolds and the exhaust, you are good to go. I didnt have them, and given the fact I would need to fab anyways, I went with the headers. Less headache and hassle.....