Mating Invida Catted DP to Magnaflow Catback

I have a Magnaflow CBE on my car currently with the stock DP, but going to be installing an aftermarket downpipe (specifically an invidia catted one) to upgrade to Stage 2.

 

I've done countless searches about this topic, and can't seem to get a straight forward answer, some say they match up fine and I do not need to purchase any adapters, others say you need to buy an adapter.

 

I know that the Magnaflow CBE has its problems because it necks down to 2.5" at the mid pipe to DP flange, but I am wondering if I can get away with just bolting the new downpipe to this flange, do they line up?

 

If not, or if it is recommended I use an adapter, is this the type of adapter I am looking for http://www.importimageracing.com/grimmspeed-3-subaru-downpipe-adapter.html and could I reuse my OEM donut gasket. Also, on the same topic; is it okay to reuse my old downpipe to turbo gasket, or should I head to the dealer and pick up a new one?

 

Thanks!

No need for an adapter. The magnaflow has a flat flange that should mate up perfectly to any aftermarket dp with 3 inch gasket.

Perfect just the answer I was hoping for, thanks! So all I need is a 3" gasket and I'm good to go

That should be all you need.

No need for an adapter. The magnaflow has a flat flange that should mate up perfectly to any aftermarket dp with 3 inch gasket.

Are you sure it's a flat flange? A few years back when I was researching a catback and compiled this thread, I came up with it being 2.5" taper for donut:

http://legacygt.com/forums/showthread.php/which-cbes-mate-up-invidia-dp-perfectlyi-115489p3.html

 

Here, more search results which appear to confirm what I said:

https://www.google.com/search?q=magnaflow+taper+site%3Alegacygt.com&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

I ran a Magnaflow for years. In fact I just pulled it off to sell. It had a flat flange and I used a 3 inch gasket to connect to my Invidia.

 

There is a taper inside of the pipe. But I believe the flange is still 3inches.

IF it looks like this:

http://legacygt.com/forums/attachment.php?attachmentid=83467&d=1271300271

 

That's a donut gasket flange, 2.5".

Edit: From this guy's FS thread: http://legacygt.com/forums/showthread.php/fs-pa-invidia-catted-dp-5eat-magnaflow-cbe-135577.html

I get that! But you should be able to add a 3 inch gasket and not have a problem.

 

There's no reason to have to worry about rewelding a different flange there when it will bolt up to your aftermarket dp with a gasket just fine.

And here's a 3" flat flange:

http://i137.photobucket.com/albums/q235/carter_briggs/exhaust/IMG_0712.jpg

 

They look similar and the holes should line up, but it won't fit perfectly. You can try to just crank it down and hope there isn't a leak, or that it won't develop a leak. Bunch of people here have done that with success.

 

But why not just get the adapter and do it the right way?

 

Personally, I lopped off the 2.5" on my SPT CBE and welded on a 3" flange to mate up with my Invidia 3" DP. But I'm a bit OCD.

I had no luck with the 2.5" taper to 3" DP thing... I also use the Invidia DP. Perhaps because I have a stock muffler the back-pressure is just too high... kept on leaking. In the end it was out with the chopsaw and on with a 3" flange. It's worth trying but be ready to have to mod your midpipe.

I have a Invidia catless DP mated to my 05's oem midpipe, I just use a 3' two bolt hole gasket. Tuner said I won't need the adaptor.

 

May be some day I'll buy the $20.00 thicker gasket...or not I think grimmspeed makes it.

 

I put a oem donut gasket in but that did nothing.

i just installed a 3" dp to a magnaflow cbe. i ordered a new 3" flange to weld to the cbe but it didnt show up yet so i just bolted the two together for now. it seals ok but it does have a realy small leak. so if you dont want to weld a new flange on, you can just bolt them together and you might get lucky. if not then you order the adapter and run around for a week with a small exhaust leak.

Or throw some rtv on the flange and bolt together and get rid of the leak and you'll save your money on the new flange and the adapter.

New flange. Adapter. Old school trick is to turn a OEM donut gasket backwards and cram it in there.

humm.. I just bought a Magnaflow cat-back ... And I wanna know if the Perrin 3'' Downpipe I have will fit ..

 

if not what do I need ?

Generic adapter or a GS adapter. It does not mate up perfect. Your DP is 3" and our CBE is 2.5"

Generic adapter or a GS adapter. It does not mate up perfect. Your DP is 3" and our CBE is 2.5"

 

So with a GS adapter it will fit perfectly ? Without leaks ?

 

yes.

I have this setup and yes you need the adapter i just had a gasket on each side of the adapter to ensure a nice seal. I love the way this setup sounds.

I also have the magnaflow and ordered the "oem" gasket through import image. I wanted the grimmspeed but they were back ordered and said this one is the same spec. Does anyone know if I will need longer bolts or if i can reuse the stock bolts when installing the adapter?

Why did you not ask IIR when you ordered???

 

Once again.... funny I am here answering tech support for things I did not sell. Lol.

 

Not sure what you mean by OEM and GS. Because GS does not sell a donut gasket. Just a 3" flat gasket. GS sells an adapter. OEM does not. YUou have GS and Chinese generic. We sell both. Also sell the OEM gaskets and the GS (as well as GTSpec and Cometic).

 

With either a GS adapter or a generic one, you will need new bolts. GS comes with hardware. Generic does not. Do not try to re-use the OEM spring bolts. You need longer, stronger Grade8 hardware. Get bolts, nuts, washers.

 

We usually use the extra hardware that comes with CNT down pipes when a customer does not have hardware. They send a bunch of extra hardware with CNT down pipes, Lol. Plus, we install a ton of them, so we have a lot of the hardware on the shelf.

I was gonna buy from you, but I added the adapter to a larger order that I was buying from them, which qualified for free shipping. if you guys had the prosport remote mount kit available, id have bought from you

by oem i meant that is what was in the description, but probably youre right it is a generic brand.

I talked to them and one guy told me that I wont need longer bolts, but from what you told me I think I do now..His experience was based of a outback though so I am not sure if there is any difference in bolt sizes between a LGT and OB

 

Ive ordered from both Infamous and Import Image and they are both great, legit sellers. Trust me I will be buying again from you very soon

We sell Prosport. But not much of it. So, I dont have it on the website. If you ask, we sell thousands of products not listed on our site. I wish I had more time to devote to updating the site, but I am spread ultra thin already.

 

You need bolts. OEM spring bolts wont even fit through the holes properly. Not to mention they are too short. Not to mention they are meant for 13ftlbs of torque (that is what the springs are there for). Not to mention the OEM flange is uber thin and the aftermarket flanges are much thicker. Not to mention that OBXT and LGT are the same. Not to mention that we actually install the parts we sell all day long and are not just an internet Walmart like many other places. So, many of the parts you see advertise elsewhere, we sell. We just dont advertise them, because our in house experience is they are not worth the money. So, we dont push them. If you ask we give honest answers based on experience. Even if it means losing the sale.

lol gotcha..any chance you have a set of these bolts for sale??

Your local hardware store is all you need. Shipping the bolts would cost about $5.