Author Topic: Removing cat on an m42? (Read 7992 times)

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!

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

kowalski · « **Reply #1 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.

sha1234 · « **Reply #2 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

denious · « **Reply #3 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:

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.

kowalski · « **Reply #4 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.

sha1234 · « **Reply #5 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

denious · « **Reply #6 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

asubimmer · « **Reply #7 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.

kowalski · « **Reply #8 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.

denious · « **Reply #9 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?

asubimmer · « **Reply #10 on:** December 25, 2006, 04:06:32 PM »

straight pipe

kevo__ · « **Reply #11 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

kowalski · « **Reply #12 on:** December 28, 2006, 01:09:12 AM »

i had a straight pipe for like 4 months. i couldnt take it anymore..

shellback · « **Reply #13 on:** December 28, 2006, 05:52:12 AM »

same as Kowalski - had straight pipe, then a generic resonator from the muffler shop.

Wizard · « **Reply #14 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....