PLEASE NOTE THAT I NO LONGER HAVE THIS SYSTEM. I GIFTED IT TO ANOTHER MEMBER OF THE R60 OWNER'S CLUB. I AM STILL AVAILABLE TO ANSWER QUESTIONS ON THE CONCEPT, ETC.

ALSO, THERE ARE NOW 6 MEMBERS RUNNING THIS SETUP, AND ALL ARE IN LOVE WITH THE SOUND AND DESIGN.

So the day finally arrived, and I made my way to the exhaust shop to get my toys installed... Sometimes being the guinea pig is fun, and sometimes it sucks. Out of all the mods and prototypes I've done thus far, this pretty much ends up in the latter category.

First, not pointing any fingers, but I asked several times what the exhaust diameter was, and was told by a couple people that it was between 2.25" and 2.5". Well, I can put that to rest and give you guys a firm answer... It's not 2.5". It's not even 2.25". At the smallest, it's 1 7/8" - at the max, it's 2 1/8" - no more.





So at least there's that - now you all know!

There was so much work involved in getting the new parts to work (welding 2.5" parts to 2" pipe sucks), I forgot to get several of the pics I needed. It's going back on the rack on Monday to get the tips installed (did not finish those today due to time issues).

The equipment I used consisted of:

1 x Magnaflow 10436 4" Resonator (28" Long) - 2.5" Inlet/Outlet
1 x BadlanzHPE Electric Cutout - 2.5" Pipe Inlet/Outlet/Blade
2 x DiMisa 4" Black Tips (Will update when installed next week!)

In order to span the gap from 2.5" pipe to 2", a lot of welding was involved - I can at least tell you it's solid without any leaks, so there's that. If nothing else, I may use some high-temp paint over the welds. Take this as a lesson - stick to 2.25" or less pipe to avoid this mess. It will look better and cost less.



I used the 10436 Magnaflow 4" resonator model, as it's 28" long. The 2nd cat and resonator remove around 26" of length from the system, so this model allowed for a direct install (no pipe needed), and kept the system 100% stainless.
Here's a picture to show you how close to perfect the fitment is on the length and the heat shield:



The 10436 is a 2.5" inlet/outlet piece. If you end up doing the same, please order the 10435 - that is the 2.25" piece. You will thank me for saving you the hassle.



I will get a better pic of the Magnaflow 10436 that replaced the cat and res shortly - I know that's sort of a requirement of the thread, but we were in a hurry to get done for today. It actually fits perfectly down to the last inch - I'm assuming the 2.25" version would be perfect.

EDIT - Here's the picture of the Magnaflow installed:



Lastly, the cutout was positioned to be 1" before the muffler - this gave plenty of ground clearance, and ensured that the exhaust gases would be vented out properly, and not toward the cabin, gas tank, or wiring. You can see the finished cutout in the earlier picture.



Now for the sound aspect: The cutout isn't very loud at all with the big 28" Magnaflow in there. Yep. You read that correctly. In fact, it's got a great low rally tone without being one bit overbearing. It's nowhere near as loud as I thought it would be. Now, when the cat and resonator were removed and it was essentially a header dump, it was very, very loud in a nasty way. It sounded less like a rally car and more like a straight-piped SRT4...



When the cutout is closed, the stock muffler in combination with the Magnaflow is nearly silent. It has a better tone, however, but remains quiet and peaceful - perfect for long drives!

I will add that there is no drone in either mode. The biggest problem with removing the 2nd cat and resonator is the addition of drone, but that long Magnaflow defeats all of that, apparently. I'm sure that's also why it's a tad quiet in full cutout mode, but I'll take that over drone any day! Remember, without the Magnaflow or another resonator there, you would hear a drone constantly right underneath the driver and passenger emanating up through the gearbox.

I took these video tonight (safely, I promise) to give you guys some idea of how it sounds from the cabin - both of these are with the cutout wide open. There's nothing much to show you with it closed - it's very quiet. Please note that in these videos, I'm trying to get it to make some noise - didn't want that confused with drone.

Normal highway driving, nothing crazy:


Having a bit of fun from a light and getting on it a few times:


Daytime driving from today - windows down:


I have a lot more (or notice a lot more) burble and pop now, and it sounds fantastic. Before they would come from the 2nd cat burning the fuel, and now they're heading down the pipe and resonating a bit more. I know not everybody likes this - I do.

This might be a point of debate, but after removing the 2nd cat, the car feels like it's breathing much smoother / free-er. I took a picture of the cat, and the density is huge for being a secondary - that's probably a 200cpi for really no reason... not smart. I guess this is why the catback makers are hacking them off...



I will keep adding to this thread as it becomes completed. My hope for this thread isn't so much to show off as it is to help you guys who want to try your hand at something new exhaust-wise. I really am not happy with how it looks under there, but I love the way it sounds both with the cutout wide open and normally muffled.

In case anyone wants to know, the total cost ended up being $375 for the Magnaflow, DiMisa tips, electric cutout, and install. I don't feel a bit bad about that.

 

Thanks very much for the writeup and pics -- very informative, sounds great

 

Added underside / Magnaflow pics, and added a daytime driving video. Tips went on today, will be posting pictures soon!

 

Finally added a drive-by 'video' with a few more clips.

Driving away 1st and 2nd gear, followed by 1st to second to stop.

 

Thanks for being the guinea pig

I did a "one ball mod" on my R53 and loved it coz it was a cheap way to get a different sound out of the exhaust. My question does the magniflow cat/resonator delete add any more significant pop or burble vs standard - a bit hard to tell with your vids as it vs cut out not vs stock. I am just looking for cheap mod for nice sound - will be looking to an ECU tune later to add some performance gains

ps I don't think the extra welding looks to hideous - just drive through some mud and it will disguise it

pps - do you not feel urge to put a small pipe on the end of the cut out - I have no experience here but it would seem quite exposed to the elements (might the flapper valve get junked up?

pps - any CEL lights ( i think I read that as there are no sensors post down pipe none should be expected

 

I do wish we had something similar to the one-ball mod here! No such luck, though.

The cat/res delete did, indeed, cause more pop and burble (in a good way, of course). The fuel isn't burning up in the 2nd cat and is going farther down the pipe now.
I've had a few friends behind me who have said (on different occasions) that they saw a few flames out of the cutout when it was popping during a decel or downshift.

This is only in Sport, and I'm usually driving for effect in those cases.

 

On a stranger note, I did a few tests the other day after noticing something...

For a 50 mile trip, I had the cutout closed, and was running through the stock muffler. I measured the MPG, same as usual - around 29.5MPG round-trip.

For the next (identical) trip - same traffic/weather/wind conditions, same speeds, etc., I ran only through the cutout. I almost fell over... 33.8MPG. Going there, I topped 37MPG (and yes, I have proof).

I did the same journey again today with the cutout open, and got 33.4MPG round-trip. For the last several months (with my current mods), I've been doing 27-29MPG.

EDIT: Look a few posts down - if you confuse the DME with altered pressure, you can get better mileage (but not for long!).

 

I suspect its a real gain that might just go away..

I assume you had battery disconnected during exhaust mods - I know the ECU self learning mode can have an affect on performance - In fact I recall some people purposely do a battery cycle before a long journey to get it into fuel sip mode

 

I have to agree 100% just based on logic. There's no way free flow would open up that much of a gap.

Oddly, it has been around 500 miles since the last battery disconnect. I'm probably pissing the learning mode off by opening/closing the valve (adding/removing backpressure).

EDIT: Yep, it's just the fooling of the DME - if I mess with the pressure, it goes into sip mode. If I leave it that way for a few trips - back down to 29MPG. Case closed there.

 

Just curious, are the various beeps in the video coming from the V1?

 

Indeed they are.

 

Well, I finally did it... I cloned theta's custom exhaust, and I must say that I love it! I went a while with only the cutout, with stock resonators and it was good, however, I like it better with the Magnaflow installed. I think it does breath a little better, although the volume is about the same with magnaflow vs stock. There is a little more 'feeling' behind the sound with the magnaflow, in that I can sort of feel the sound in the seat.. It's a more abrupt, throaty sound, compared to the more ambient droan type sound of stock with cutout. Sorry if those adjectives are confusing, but it's very subjective. The only changes I made are that I went with the 2.25" pipe size, and the exhaust shop put on a little down pipe to direct the gases out.

 

Found this thread searching through the drivetrain mods section.

I just thought I'd respond to this specific part... you're measuring the inside diameter of the exhaust pipes.

Typically, exhaust pipes are measured in outside diameter. That means that depending on wall thickness, two of the same size tubes will have different inside diameters. Luckily I think most are around .065 wall so you wont have big steps in your flow path.

The exception to this is stuff like mufflers or cats. They are designed to slip-fit over the tubing so they will have short pipes that are sized with an inside diameter slightly larger than the nominal OD of your pipes.

Just something to consider.

Other than that... nice work on the build. I'd love to build myself a countryman exhaust. I built myself a complete turbo-back system for my miata and am hugely satisfied with it. 3" pipe is hard to fit under a tiny car though!

Here's my first system that was too loud (small muffler):



Here is the updated rear section with the giant magnaflow straight-through:



I think that same giant muffler would do well for the Countryman as well--it's barely more restrictive than a straight pipe. Kinda looks like this on the inside:



The only issue that is painfully obvious is the single-in single-out design and we have dual pipes. I dont think there's room enough for two mufflers back there. Here's some google image search ideas:







Man, that got long. Sorry for hijacking this thread.

 

nice write up!

 

Theta,

Can you confirm what the diameter is of the pipe from the flex joint to right before the second cat? Basically, the area between the DP and the flange on the far right of the attached photo?

I know the mouth of the DP is 2.5" and it necks down to not much above 2.0." The question is where? I'm hoping it's after the flange on the right, but I'm doubtful.

Also, the second photo is another possibility for dual mufflers in the rear.

 

From the Flex Joint to the 2nd Cat is 2.25" give or take. And it only gets smaller from there...

You're correct about the 2.5" from the DP, though.

EDIT: For the record, that front engine/exhaust part looks different than mine...

 

Thanks for the prompt reply. That's what I thought; 2.25". Too bad. I think the difference between yours and mine is because mine is just an "S," no All4.

 

I saw that from the rear axle. I can't really say for 100% certain that yours isn't 2.5" -- but in my case, the flex back was only 2.25".

I hope to remedy that shortly.

 

I suppose I could measure the circumference of the pipe to get a sense of the outer diameter, right? Hmm.

 

Absolutely!

Exhaust diameter would be the circumference divided by 3.14159 (pi). I would take a few hairs off the circumference to adjust for pipe thickness, error, etc.

 

Using a wire, I measured the circumference at a hair under 8". According to an online calculator, an 8" circumference equates to a diameter of 2.54" inches. Similarly, a circumference of 7.85" equates to a diameter of 2.498" inches.

Looks to me like it might actually be about 2.5" right before the cat. Good to know, I guess.

 

Wow - that's awesome. Mine is for sure necked down to 2.25 in 4 places. Staring at the pipe literally right this second. Will take a pic.

 

Pics

 

That does look a bit different than my setup. I should have taken a few photos while I was under there. Now I'm going to have to jack it up again.

I might actually grab a more pliable tape measure, too, so I don't have to use a wire and transfer to a yardstick.

 

Might be an All4 thing.

With pipe, the smallest diameter equals the total diameter due to flow... Just like a water pipe etc.

Sad to see that on mine.