[shatty]

So I looked under the car. I saw (2) dual resonators/mufflers in the middle. Also saw (2) single mufflers or resonators toward the front. Tomorrow I am going to the shop and they are going to cut out the (2) dual mid resonators. I am replacing them with a 3" SS x-pipe found on Amazon, 3" galvanized steel flex pipes from AutoZone, and 3" SS extensions to join the flex hoses to the single resonators. I measured the exhaust under the car. Looks like 2.75" OD piping. This stuff getting welded. I dont wanna remove the single resonators yet because I want to see what sound I get from removing the 2 duals first. Dont want it so loud. Esp with these audio detecting devices NYC is putting up. If I want it louder after 100-200 miles, then I will remove the singles. I will take pics as they are progressing with the job. I will list the parts used when the job is done as well as links and measurements. Well under what these companies are selling theirs for. Might need the flex hose to bump up above the brace between the 2 duals. I will try straight pipes first without using the flex to see if it clears. The duals height waranted a bent pipe between the duals. The xpipe is not as high si it will sit higher and might not need flex pipes. Parts cost so far is around $97. $39 for xpipe, $38 for 4' 3" SS pipe, and $10 for flex pipe x 2. I am estimating $250 for labor. So thats $350 compared to 700 for dinan or 1300+ for others. Problem is those pipes delete the single resonators. In the future if I want to take them out, I could just buy another 3" pipe and cut them out and weld in the 3"., Bottom pic is the (2) dual res. Top is (2) single res. Stock exhaust is so muted. Look at this setup with 3 res per side.

[shatty]

Also force opening the flaps to complete open then pulling the fuse. Gunna check the wiring and see if 12v would fire up the motors on them. I want them 100% open and flat when I pull the fuse. Bimmerlink confirmed that flap control doesnt work with G87. Also tried with ISTA and they only open them 25% for "install mode". Not buying a $900 controller to control them. Sounds stupid. Has to be a device that connects to the actuator plug and has a relay to open and close them with remote and is 12v powered.

[M_Power Rob]

Not going to comment on the shatty exhaust job but a valve controller is not $900. Either you youbarent looking it up correctly or someone is ripping you off.

[shatty]

Sorry 285-520 for controller. But I want them open 24-7. Rather force them open and pull the fuse. A lot cheaper.

[Jack@AUTOID]

Originally Posted by shatty

Sorry 285-520 for controller. But I want the open 24-7.

You're gonna get a lot of drone if the valve is open 24-7. Best off getting a controller.

I would also try and avoid any flex hoses. They will not last.

[M_Power Rob]

Originally Posted by shatty

Sorry 285-520 for controller. But I want them open 24-7. Rather force them open and pull the fuse. A lot cheaper.

If you pay more than $250 for the controller you are getting ripped off. Hey, if you prefer to rig everything vs being able to do it so you have control (there may be times you want or need the valves to be working not 100% open), its totally your prerogative.

I also wouldn't be hacking up the exhaust like you plan, but hey, different strokes...

[nickyjimz]

Always keen to see DIY jobs, especially with photos. Thanks for sharing OP.

[aerobod]

Perhaps best to just remove the exhaust system from the downpipe to the back box and fabricate a new system in stainless steel pipe. If it remains uncut it can easily be replaced if things don't work out or if the car needs warranty work that the exhaust may affect.

Also, when removing the central brace it is important to replace the fasteners with new ones and torque them correctly, otherwise body flex or noise may develop. The details will be in the BMW ISTA on how to do that correctly.

[M_Power Rob]

Originally Posted by aerobod

Perhaps best to just remove the exhaust system from the downpipe to the back box and fabricate a new system in stainless steel pipe. If it remains uncut it can easily be replaced if things don't work out or if the car needs warranty work that the exhaust may affect.

Also, when removing the central brace it is important to replace the fasteners with new ones and torque them correctly, otherwise body flex or noise may develop. The details will be in the BMW ISTA on how to do that correctly.

Or, use a Sawzall (with random clamps and welding) fuggedaboutit...

[JG13]

Lol @ the elitism in this topic.

There's nothing wrong with going the DIY route here. They're just metal pipes.

[Geighty7]

Originally Posted by JG13

Lol @ the elitism in this topic.

There's nothing wrong with going the DIY route here. They're just metal pipes.

Yeah but…AA single or EL mids >>>

[two_three_two]

Originally Posted by JG13

Lol @ the elitism in this topic.

There's nothing wrong with going the DIY route here. They're just metal pipes.

I for one support this creative endeavor and am interested to see the results... on someone else's car

[M_Power Rob]

Originally Posted by JG13

Lol @ the elitism in this topic.

There's nothing wrong with going the DIY route here. They're just metal pipes.

Dont forget the use of the quality flex pipes.

Your opinion and you are obviously entitled to it. I for one did not buy the M2 nor modify my M2 for the sound it makes. Some choose to spend $70k and then treat it like a used moped...

Will the DIY hack job be designed for its flow to work in tandem with the motor and turbos? Oh wait, never mind...that has been answered (strictly for noise).

[MrTiger]

Originally Posted by JG13

Lol @ the elitism in this topic.

There's nothing wrong with going the DIY route here. They're just metal pipes.

Do it

[JG13]

Nothing wrong with buying exhaust from AA, nor is there anything wrong with a member here creating their own solution. We should be applauding people for testing things out for the community instead of dunking on them.

And again, it's an exhaust. It's not that serious. I'd be willing to wager if you dyno before and after, there will be some small power gains removing these restrictions.

[AZG87]

The hatchet job aside I also wouldn't opt for galvanized steel over 304 ss. If you're going to cut it up at least use the better materials.

[M_Power Rob]

Originally Posted by JG13

Nothing wrong with buying exhaust from AA, nor is there anything wrong with a member here creating their own solution. We should be applauding people for testing things out for the community instead of dunking on them.

And again, it's an exhaust. It's not that serious. I'd be willing to wager if you dyno before and after, there will be some small power gains removing these restrictions.

There is A LOT more to the car than a dyno figure (which really in itself, has nothing to do with modifying or replacing your exhaust). There is a reason exhausts are flow tested (hint...its not for noise).

Of course, as you say, its JUST an exhaust, what does it matter.

Look, I dont really care what you all do with your exhaust. It won't effect me in the least bit. People try and help and they get shit on. Have fun with a herky jerky piecemeal welded exhaust...

[Kevin_The_Clean1]

One of the guys I use to work with at TESLA recently did this very same thing on his G80 M3 & it sounded pretty decent. He hasn't reported any drone yet & he's got a 6-speed manual too.

[shatty]

I did it. Here come the pics. No bends needed. Used X in the front and then straights to the back. Removed the Flap controller and removed the spring and little circle piece so the arm from the controller doesnt reach the flap. Did a small weld to hold the flaps open on outside. In s+ and M sound on, the f'in car will burble till no end. Mid RPMs are awesome. Cold start is loud.

[shatty]

Originally Posted by aerobod

Perhaps best to just remove the exhaust system from the downpipe to the back box and fabricate a new system in stainless steel pipe. If it remains uncut it can easily be replaced if things don't work out or if the car needs warranty work that the exhaust may affect.

Also, when removing the central brace it is important to replace the fasteners with new ones and torque them correctly, otherwise body flex or noise may develop. The details will be in the BMW ISTA on how to do that correctly.

Anything after the downpipes (cats) can not affect the warranty.

[shatty]

Pipes in the back are almost rectangular at the cut. They welded everything and also pushed the exhaust up while welding with these screw up hoists so the 3" pipes clear the center brace. You get a SLIGHT drone with this setup with flaps always open. I also believe there are flaps toward the front of the setup near the downpipes. The M sound button will turn on and off burbles if in S+ engine mode. Feels like the M sound does nothing in efficient.

Next mod is front mount intakes from RK or BMS. RK has the colored ones. I would get the white pipes with black filter. Then after break in I will do the intake and JB4. I have the Rogue shifter but need to be under car to detach. I should have done with exhaust out. Now hopefully I can detach from front at DP's and get to it from there or maybe not even detach the exhaust.

[shatty]

Heres pics of the car. Also bought JBWeld stick to go over the welding job and if I see any little holes, i can plug them up.