M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: denious on December 25, 2006, 02:46:15 AM

Title: Removing cat on an m42?
Post by: denious on December 25, 2006, 02:46:15 AM
I'm replacing my whole drive shaft, so while I'm at it I decided to replace the Sunfire cat-back from the PO too! :D

So, I was thinking of making a custom exhaust; meaning pipe/muffler instead of cat and a turbo magnaflow (:cool:) as the rear muffler. (And no, I do NOT care that Magnaflow is rice, apparently it sounds very nice on the 318is from what I've heard, costs $40 and has dual tips).

My question is, what damage will be done in terms of power and noise (not environment) if I run catless or have a muffler instead?

Answers, Comments, Your setup? ;)

PS: I'm trying to keep the new setup around $200-250
Title: Removing cat on an m42?
Post by: kowalski on December 25, 2006, 02:49:07 AM
a side note: look at the rear valance. you will have to cut to get dual pipes. i have a magnaflow and it sounds pretty good.
Title: Removing cat on an m42?
Post by: sha1234 on December 25, 2006, 12:11:58 PM
well are you gunna keep to 2.25 or go 2.5 piping.... if so are you gunna get a custom mandrel bend stuff or just a few U's and cut weld em together
i went from the cat back with 2.5 inch mandrel stuff, i cut welded it back, it rubs when i go in parking lots going up or down floor to floor unless i go sideways
but thats a side thing....
when i was running no rear section... only cat, it ran well, i thought i would have no back pressure or anything, but i still had plenty of go, i could still get the tires to kick out, and could still pull the same if not better than before
once i put on a FLOWMASTER 40 series (highly recomended by me) things only got better
i could knowtice that the whole car's power band had be tightened up and was a nice few ponies for 150 bucks...
and it wasnt a droning noise, like what I've heard from other E30's with some mufflers
nice burble at lower rpm... from idle to about 3000 from then on its just angry and pretty loud its super nice
Title: Removing cat on an m42?
Post by: denious on December 25, 2006, 01:09:11 PM
Quote from: kowalski;16172
a side note: look at the rear valance. you will have to cut to get dual pipes. i have a magnaflow and it sounds pretty good.

Do you have any pics of what it looks like? Or even a video maybe?

Quote from: sha1234;16176
nice burble at lower rpm... from idle to about 3000 from then on its just angry and pretty loud its super nice

I want to keep it 2.25 mandrel bent, I don't see a big point in running 2.5 only cat-back anyways. Flowmaster, you say? I dunno which is gonna sound nicer, Magnaflow or Flowmaster... By nice I mean deep in low RPMs but still not screaming as it goes higher.

Would you have any pics or/and a video?

The stock exhasut system:
(http://img318.imageshack.us/img318/2173/4f1iy4.jpg)

Now what I thought is getting a resonator or a cheap cat, and replacing the rear muffler with the dual exit one from Magnaflow; apparently I'll need to cut the valence but it's worth it IMO.
Title: Removing cat on an m42?
Post by: kowalski on December 25, 2006, 01:12:47 PM
flow master sounds like ass. I used to have one on my car. the magna flow has a much  better tone to it.
Title: Removing cat on an m42?
Post by: sha1234 on December 25, 2006, 01:32:18 PM
meh.. maybe you had a different one or whatever... or maybe its just a prefrance...
i got the 40 series with delta flow technology... apparently that changes the sound a bunch who know... they said it was a better muffler so i got it
as for pics or videos i have a few pics that i will post to show
its not 100 percent complete.. i need to re do the hanger so it sucks up to the body more
and the muffler clamp is beeing custom made right now
(http://i100.photobucket.com/albums/m24/sha1234/Picture213.jpg)
(http://i100.photobucket.com/albums/m24/sha1234/Picture215.jpg)
Title: Removing cat on an m42?
Post by: denious on December 25, 2006, 02:02:05 PM
Doesn't look so bad but as kowalski said, somehow I think that the Flowmaster will sound more ricer style... Check out that vid guys and tell me if your cars sound anything like that?

http://www.youtube.com/watch?v=N1pPu6VoL8s
Title: Removing cat on an m42?
Post by: asubimmer on December 25, 2006, 02:03:33 PM
yeah you don't need a cat w/ the m42.  I took mine off a few days after I bought the car, but we don't have emissions in NC for obd1 and older.
Title: Removing cat on an m42?
Post by: kowalski on December 25, 2006, 02:16:22 PM
I had a delta flow 50 series. both the 40 and the 50 series are basically the same except the 50 series is a little more quite then the 40 series. I will admit, the idle sounds mean, but from 1,000 rpm to about 3,000 it sounds like ass, no offence, if you like it thats cool but its not my cup of tea.
Title: Removing cat on an m42?
Post by: denious on December 25, 2006, 02:28:08 PM
Quote from: asubimmer;16191
yeah you don't need a cat w/ the m42.  I took mine off a few days after I bought the car, but we don't have emissions in NC for obd1 and older.


What'd you put instead? A straight pipe or a resonator?
Title: Removing cat on an m42?
Post by: asubimmer on December 25, 2006, 04:06:32 PM
straight pipe
Title: Removing cat on an m42?
Post by: kevo__ on December 27, 2006, 06:43:48 PM
how do all,
 so how many cats does it have? cos i was told mine had three 1990 uk spec 318is (of course). kev
Title: Removing cat on an m42?
Post by: kowalski on December 28, 2006, 01:09:12 AM
i had a straight pipe for like 4 months. i couldnt take it anymore..
Title: Removing cat on an m42?
Post by: shellback on December 28, 2006, 05:52:12 AM
same as Kowalski - had straight pipe, then a generic resonator from the muffler shop.
Title: Removing cat on an m42?
Post by: Wizard on December 28, 2006, 08:34:22 AM
Quote from: kevo__;16304
how do all,
 so how many cats does it have? cos i was told mine had three 1990 uk spec 318is (of course). kev


Kev,
check our realoem.com
I looked at the Euro verson our cars and it shows the exact same exhaust system....Only has 1 CAT....
Title: Removing cat on an m42?
Post by: denious on December 29, 2006, 12:33:44 PM
After a lot of thinking I guess I'll go with taking the cat off, putting a long resonator instead and a Magnaflow muffler. I don't know if I'll get a Magnaflow resonator or just a cheap one? Anybody know if it'll get louder WITH the Magnaflow one??
Title: Removing cat on an m42?
Post by: ///Motorsport on December 31, 2006, 01:38:50 PM
Haven't hread the thread yet, but I just did a catless setup, straight pipes to a remus muffler. Ill post a thread later today with details, its loud.
Title: Removing cat on an m42?
Post by: denious on January 04, 2007, 11:15:38 AM
It's done! The exhaust has been installed!! :D Resonator instead of cat and a "Raptor" muffler lol (like that one (http://www.holley.com/data/products/pictures/large50054.jpg) but no offset) and it sound pretty nice. A little raspy but it'll go away in some time. A clip will be done when I'll replace the driveshaft, so next week.
Title: Removing cat on an m42?
Post by: E30_318is on July 03, 2008, 05:59:45 AM
Hi!
Im going to remove a cat. from my stock m42 muffler.Im planning to replace a cat. with simons resonator ( in & out 2,5" : lenght 25") (http://www.ostuauk.com/images/products/s406.jpg)
How could this setup sound? I hate raspy & 2 loud exhausts. (http://youtube.com/watch?v=LhnyNorCqlk )

This exhaust is :cool:
http://youtube.com/watch?v=qUauaynLb5o

Any suggestions?



Sorry for my English.
Title: Cat removal
Post by: 91318isguy on July 03, 2008, 08:35:11 AM
I've been through this twice. My first IS I had a standard exhaust with a leaky cat, so it sounded like dog doodoo anyway. I went to the muffler shop and got a Flowmaster (I believe it was 40 series) installed and a high flow cat cut installed. I'm with E30 318is on this.

I CAN'T STAND when my exhaust is compared to a civic's. On the above example, it was a tiny bit more throaty, but LOUD AS HADES. I'm kinda glad i wrecked that one. On my current project it came with a high flow muffler (I beleive it might be ANSA, I'm not exactly sure though) and stock cat. My mechanic did something for me and looked over the car, said my cat is stopping up. His recommendation was that since it's OBD1, cut the cat off and straight pipe it.

Here's a thought... I saw a company named Tanaka I beleive, or maybe it was Greddy and the exhaust series was Tanaka... anyway, they made a stock sounding exhaust, but had high flow muffler number increases... that's what I'm probably going to try to get next... I'm taking my cat off next week and putting on a resonator in place.

I know it's against the grain in the modding world, but I like a sleeper sound.