M30 exahust

[azzkikr]

What did you M30 owners out there do for exhaust. Specifically I am concerned with the muffler. Did you use a stock E30 muffler or did you use the M30 muffler and if so how did you mount it? That seems like the E30 muffler would be a huge bottleneck in the flow but I dont know. The pipes are smaller if nothing else. I am probably just going to go buy some 2inch pipes and make my exhaust but I wanted to see what others did first. I am probabbly going to remove the cat all together and call it good. Anyone do anything special? I suppose straight headers is not an option anymore.

[vance335is]

m30 exhaust

I had already replaced my stock e30 muffler with a magnaflow so i just got rid of the cat and ran the pipes from the exhaust manifolds straight back to the muffler.

[asubimmer]

who still has cats?

[azzkikr]

Did you use a magna flow for the 3 series? Do they make a muffler for the 5 series? I couldnt find anything on their site. I am just concerned with flow issues. If I use a 3series muffler is it going to be too restrictive for the big 5 series motor?

[azzkikr]

who still has cats?

The cat will be gone for sure! :-)

[asubimmer]

haha I was just messin but I'm glad you are gonna toss them. You want a dynomax or magnaflow universal muffler. You can have a shop weld it in for you. The dynomax is like $40 and sounds great, not to mention it is a turbo muffler so it will flow good.

[rs4pro3]

for my exhuast I used a 535i downpipe, dual high flow 2.5" cats, and then a stock 325i muffler. It sounded perfect, quite around town but once you got above 3 grand it just would roar.

[E30/M30]

I'm using a chopped E34 535 down pipe with a Scorpion E30 M3 exhaust, no cats

[Garageaholic]

I got a magnaflow 14833 series muffler and am going to do straight pipes 2.5" down... i got a guy to do a custom job for me using autozone 45* bends... i'm gonna go single 2.5" all the way through..

I dont know how he's going to mount the muffler, but you can always just weld a piece of steel rod to the body of the muffler (the ends of it) and just make a loop to go into the stock rubber E30 muffler hangers...

[Garageaholic]

Guys,

if any of you used the motormounts (type II) from e30.de, did the stock downpipes clear the engine mount??

[E30/M30]

The down pipes clear my E30.de mounts(not sure which type they are now but it's an E34 M30), but mine needs re-doing as it's a bit to close to the lolly pop

[bmw335ist]

My first project i used Magnaflow and m30 down pipes and "Y" them together and put my O2 sencer right after the "Y" right under the car 2 1/2 pipe NO cat, But I knew I would be doing some intake work that is why I chose 2 1/2" when I was done I added Throttle body,intake manifold for more breathing the car sounded really nice with enough power. The turbo was a diffrent story.

[azzkikr]

Looks like 2.5'' pipe is the way to go. I think I am going to run the stock M30 downpipe and butt joint on some 2.5'' pipe. Then I am going to Y that where the cat would be put the O2 behind that and run a single 2.5'' pipe to the stock E30 muffler. I guess I will have to Y it again because the E30 muffler is dual pipes I believe. Does that seem like it would produce good unrestricted flow? I dont care much about the sound just the flow.
Did you guys have to use any huge bends? I cant image you would. I think 45 like M3fan4eva used would be all that you need. I assume I will follow the stock path and just run the pipe.
How hard is it to bend steel pipe? I have never bent it before... well except for break lines but that is different I assume. If I just use a big version of a break line bender will that work? Should I heat the extending side first? I assume I will use 2.5'' 16 gauge pipe. Any thoughts on this?

[bmw335ist]

if you use 2.5" pipe that is a little big so if you have little restrection it should work good. (I would use 2.5")
The exhost is the only part this swap that if you want it perfect then you will have to spend the money, That is you find a shop that build's exhost for race cars.
I had my step dad build my exhost he also works on a race team.
when I had my exhost done both times first thing they did was mesure the throttle body to find out how much air was going in and then some formula for the intake/stock head they had to add in with that any way $600 for the exhost and a used magnaflow 2 1/4 so he made it fit

[Garageaholic]

Ok, here's what im going with and i'm welding it up next week. 2.5" from the stock headers, then down to a y pipe... then putting a flange (so i can disconnect it if i need) to a high flow cat. then 2.5" single all the way to my magnaflow muffler.. Sticking with that and we'll see how it goes... can't wait...