Author Topic: Custom Exhaust Build (Read 3181 times)

bmuser · « **on:** July 26, 2007, 08:54:12 PM »

Hey guys i just bought my first 318is, its my second BMW but im loving this one more. It has an exhaust problem. The previous owner had the exhaust rebuilt. It looks like the piping from the headers to the cat is new, as well as the cat. After the cat into the muffler back im not sure but could easily be new as well. The car makes a lout rattling sound at full WOT, and the owner says that when they did the exhaust they probably accidentally dropped a washer/bolt/somethign into the cat which is making hte sound. I had the car on a lift with the engine ON and the sound DOES come from the cat, however the cat looks new. I went to an exhaust shop and the guy told me that i would need a new cat. Whatever. I was thinking either way of getting a high-flow cat, and some nice muffler like a Dynomax or a Magnaflow or whatever, just so that it fits the size but is less restrictive.

What are your guys' thoughts. Have any of you done custom exhausts? I dont want to buy a new one, id want to build one, but i dont have exhaust building equipment so i'd be going to an exaust shop.

91318isguy · « **Reply #1 on:** July 26, 2007, 09:32:10 PM »

Hi, and welcome to the club. This is my second M42. I got a high-flow exhaust on my first from... crap, I don't remember the name. I'll get the name of the company and get back to you. The factory cat sounded horrible. It only cost about 35 dollars. It made the car sound better definitely, but most importantly it made the car perform better.

My current exhaust sounds lovely (I'm about to get it on the road, so I'll post pics soon), so when this cat wears out, I'll go back to the same company.

sumyungguy · « **Reply #2 on:** July 26, 2007, 10:25:50 PM »

Does it have a resonator? Mine didn't when I got it and it made all kinds of sounds. I just went to a muffler shop and had them build a catback with a resonator and a stock like muffler all in 2.25.

There it is on the ground (the mounting postions are different now, I got some metal brackets with big poly bushings bolted to the chassis, you can baerly see one between the muff and resonator)

Here's a rear shot

Bill-B · « **Reply #3 on:** July 26, 2007, 11:38:15 PM »

I run catless, with a resonator in place of the cat, with stock piping back to a Dynamax Super Turbo Muffler. 5 people so far have told me it sounds like an E46 M3:cool:

D. Clay · « **Reply #4 on:** July 27, 2007, 12:04:36 AM »

Cats can make a sound like a heat shield rattling. The only fix I've had any success with was replacement. Well, once I had a rear muffler with a loose baffle. I pushed on it with a hammer handle and it quit so I started putting screws in it from the outside. The third one caught the loose baffle and it never rattled again. That is the offficial BMW factory authorized repair if you were born where I was, that is, so far up a hollow in Appalachia that even the Presbyterians handled snakes.

bmuser · « **Reply #5 on:** July 27, 2007, 10:14:01 AM »

Alright. Sounds like i need to design a new exhaust. The piping from the headers to the cats is new. Now, do these cars have 2 cats? Or is one a resonator? Its probably a resonator. If i take that off will it be really loud? Basically i'm planning on getting a hi-flow cat and a dynomax muffler and have a shop weld everything on. I was thinking of getting these from ebay. Anyone have any other suggestions on where i should get this stuff?

gearheadE30 · « **Reply #6 on:** July 27, 2007, 08:47:15 PM »

The first is a cat, the second is a resonator. A great place to get stuff for the exhaust on the cheap: Summit Racing. Google it

.

Taking the resonator out sounds like crap on the M42. I suggest keeping the stocker or getting something like the flowmaster hushpower.

oldtimer · « **Reply #7 on:** July 29, 2007, 08:14:43 PM »

Okay I scanned some of the reply to the original thread, take it form a guys who learned a hard lesson on taking the "cat and the resinator" off and going straight 2 1/2 pipes with just and perfomance muffler. YOUR CAR WILL SOUND LIKE A RICER, that's saying that from experienced to fix the problem I had to re-install a high flow cat and resinator. I now drive 381is daily due to the sound of real performance well tune machine. I advice you not to eliminate the car and resinator unless you like you "Bimmer" sounding like a ricer if so. Go get yourself a "honda".

Shocker · « **Reply #8 on:** July 29, 2007, 10:51:20 PM »

Quote from: oldtimer;30689

Okay I scanned some of the reply to the original thread, take it form a guys who learned a hard lesson on taking the "cat and the resinator" off and going straight 2 1/2 pipes with just and perfomance muffler. YOUR CAR WILL SOUND LIKE A RICER, that's saying that from experienced to fix the problem I had to re-install a high flow cat and resinator. I now drive 381is daily due to the sound of real performance well tune machine. I advice you not to eliminate the car and resinator unless you like you "Bimmer" sounding like a ricer if so. Go get yourself a "honda".

It all depends on what combo your running. My car absolutely doesn�t sound like a Honda. I have a magnaflow round muffler in place of the cat with the stock resonator with a series 50 flowmaster muffler out back. Now it sounds different but not raspy at all and not loud (sounds/picture clip coming).