E46 330i minus cat

Bennie · Jun 15, 2010

Hi Everyone

I'm new to BMWfanatics and at first put this thread in the :wrongforum: ...sorry bout that!

Anyway, I want to ask a question I'm fairly sure has been asked before:

What kind of power gains can I expect by removing the cats on my E46 330i and fitting a Viper freeflow manifold? I'm not having the entire exhaust done, only the manifold.

Any info will be much appreciated!

Thanx,
Johan

ChrisBrand · Jun 15, 2010

Welcome to the forum

I have a e46 328i and gained a claimed 12kw from just removing the cats. Hope that helps

Kotters · Jun 15, 2010

Slim to none...

you will not feel the difference!

STREETRACER · Jun 15, 2010

doing the branch and full TNT freewlow you can expect up to 15kw and you will feel it!
Cat gain depends on the milage and if they are blocked yet!

Bennie · Jun 17, 2010

Thanx for the info. The car has done around 180 000km. Somewhere I heard cats only last around 150 000kms...Don't really know what that means though...Anyway I'm having it done as I'm writing this...

M3_FTW · Jun 17, 2010

Bennie said:
Thanx for the info. The car has done around 180 000km. Somewhere I heard cats only last around 150 000kms...Don't really know what that means though...Anyway I'm having it done as I'm writing this...

Cats are only really good up to 70 000 km's. My Cats were removed off my E46 M3 @ about 170 000 k's. Clogged like a M^&*())(*&ER

Gizmo · Jun 17, 2010

Remember, your 330i has 4 cats. Two in the headers and two in the exhaust, you need to eliminate all the cats for it to be worth it.
Just have Abel build you a custom s/s exhaust system with the Viper headers and you will have the sweetest sounding 6cyl engine. Plus the fact that it optimizes the engine performance and gives you better gas mileage.

I have TNT E36 328i headers and a dual 57mm s/s freeflow system done by wildcat on my 330i. It runs extremely well compared to stock and it sounds absolutely perfect, ask anyone who has heard it.

Bennie · Jun 22, 2010

Gizmo said:
Remember, your 330i has 4 cats. Two in the headers and two in the exhaust, you need to eliminate all the cats for it to be worth it.
Just have Abel build you a custom s/s exhaust system with the Viper headers and you will have the sweetest sounding 6cyl engine. Plus the fact that it optimizes the engine performance and gives you better gas mileage.

I have TNT E36 328i headers and a dual 57mm s/s freeflow system done by wildcat on my 330i. It runs extremely well compared to stock and it sounds absolutely perfect, ask anyone who has heard it.

Thanx, Gizmo. Only just saw your reply. I will keep this in mind since I did only have the 2 cats in the manifold removed... Also, I have some oil use problems on the 330i. I have posted another thread but don't know how to link it to this thread. I posted it 20mins ago, if that helps. You will read there that I'm at a bit of a loss...Any advice will be welcome!

Johan

Dwayne_Russell · Jun 24, 2010

Hi guys,

Another newbie here!!
Along the lines of Bennies Question, if all four cats are removed, and simply replace them with tubing, will this change the sound for better or worse, and will there be any power gain? if so any idea how much?? Otherwise is it more advisable to do a full system? also gana be going some software.... any recomendations??

San · Jun 24, 2010

@ Dwayne_Russell,

The 2 cats on the manifold cannot be replaced with tubing, you will have to get a branch to replace it. ( Aftermarket or E36 325/328i hearders..) The cats under the car can be replaced with tubing..
I suggest you add on 2 sausage / round boxes in replacement of the cats under the car or else, you will get a very raspy / tinny noise which can be irritating. The car will feel abit better but not a huge difference.
I suggest you go with a full system, if you going to do software. :thumbsup:

Dwayne_Russell · Jun 24, 2010

Great sounds good, many thanx.
Exhaust and software specialist recommendations??

San · Jun 24, 2010

Software, Speak to Excede Performance and Exhaust shops, you can try Viper, TNT or Wildcat.. Check with prices and the system size they will be installing...

Bennie · Jun 25, 2010

Hi Everyone

Had the 4 cats removed and the car is definitely more responsive! Not a helluva lot, but definitely better. I had a Viper branch fitted in place of the standard manifold and replaced the secondary cats with stainless steel resonators from Powerflow. Also, I plugged the vacuum pipe supplying the little disc in the one exhaust outlet with a bolt (M5 or M6 thread, can't quite remember the size), so both exhausts are now open. I did the same on my E36 328i a few years ago.

The car is a little louder, but, importantly, at highway cruising speeds it is not intrusive. One of my favourite things, though, is driving along at town speeds with the window down - its got a really nice smooth and deep burble.

Also, BTW, regarding the oil use as I mentioned in one of the previous replies, it seems the oil consumption has now settled at around the halfway mark on the dipstick...I kept topping it up and the car seems to keep using oil intil it reaches the dipstick halfway mark. Perhaps only an incorrect length dipstick???

Johan

STREETRACER · Jun 25, 2010

but get a dastek uniQ chip now fitted and get it tuned accordingly! then you will feel the difference!

Gizmo · Jun 25, 2010

I've been pondering a chip on the 330i, costs?

STREETRACER · Jun 25, 2010

R3000 fitted and mapped!

bimmer330 · Jun 25, 2010

Dude.
I had the Viper branch done with their free flow.
no chip installed yet but I do have one in the garage removed from my old car.
I have raced same model than mine with only free flow done. mine is faster.
I have reced same model than mine standard. Mine is faster.
I have reced Z3 with 3.0l engine. Mine is faster.

I think removing cats and replacing system with branch and free flow does help.

Epoc · Jun 25, 2010

Hi Bennie,

Any issues with the sensors?

Thanks

Bennie said:
Hi Everyone

Had the 4 cats removed and the car is definitely more responsive! Not a helluva lot, but definitely better. I had a Viper branch fitted in place of the standard manifold and replaced the secondary cats with stainless steel resonators from Powerflow. Also, I plugged the vacuum pipe supplying the little disc in the one exhaust outlet with a bolt (M5 or M6 thread, can't quite remember the size), so both exhausts are now open. I did the same on my E36 328i a few years ago.

The car is a little louder, but, importantly, at highway cruising speeds it is not intrusive. One of my favourite things, though, is driving along at town speeds with the window down - its got a really nice smooth and deep burble.

Also, BTW, regarding the oil use as I mentioned in one of the previous replies, it seems the oil consumption has now settled at around the halfway mark on the dipstick...I kept topping it up and the car seems to keep using oil intil it reaches the dipstick halfway mark. Perhaps only an incorrect length dipstick???

Johan

STREETRACER · Jun 25, 2010

it does help for sure but will help even more if you do the chip!

clutchplate · Jun 25, 2010

cool, hey SR how much is the uni-Q+ versus the normal uni-Q ?

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