Gen III M&M Header install DIY.

[FLATOUT]

I picked up this set from the guys at M&M here on the board and got them installed this last week. All in all I'm very happy with the construction, price, performance, and fit and finish of the headers. The customer service I experienced was exceptional and install was a breeze as far as header installs go.

I went ahead and took a few pics during the install, nothing to detailed as we already had an install document on the site but thought I would comment on the things that worked well and or things I did differently.

First a few things I did before getting started. The M&M turnouts are 3 inch and my Corsa has the 2 1/2 inch inlets so I needed to get a reducer made at a local exhaust shop. Super cheap and quick. I went ahead and threw the catback in my Jeep along with both turnouts to make sure the fit was as tight as possible. I would later weld the reducer to the turnouts once cut to length but for adjustment purposes need these to be movable.



Next per our install doc here I went ahead and ordered new Mopar exhaust manifold gaskets just incase my stockers separated upon removal (which they did.) These are cheap anyways roughly 36$.



***Note: M&M states to not use these copper gaskets as they can lead to warping of the collector flange over time, it's instead recommended to use High Temp RTV instead.

Leaving this here simply for part number reference
Next I went ahead and called up Summit and ordered new ARP hardware (not necessary, but recommended) along with some copper gaskets for the collectors. These are also not mandatory but they don't cost much and do the job well.





Once everything came in, I went to work. I ended up doing the install alone which is doable, but I took my time over the coarse of a week to get everything done right. First things first, got the side sills removed and the catback off.



Next I removed the windshield cowling, airbox, and the cabin airfilter plastic housing at the base of the passenger side windshield cowl.



Here I kind of skip ahead in the pictures so i'll give a quick breakdown. Removed the wires, valve covers, loosened the coolant overflow and secured it out of the way. Removed and marked the throttle cable position, removed the break booster line and folded out of the way. Basically try and create as much clearance as you need to remove the old exhaust manifolds and install the new headers. I secured the fusebox heat-shield back with a long piece of blue painters tape secured to the fender (I know it looks hillbilly, but it works great.) From here, protect your rocker arms and cylinder heads from damage as you remove the stock manifolds and install the new headers. I didn't take any pics but I used tape and rags which worked fine. Here it is all torn down.





From here I inserted a couple of set screws into the head to hold the new gasket in place and to hang the new headers on (more detail on that in the original install doc.) Use antisieze, and the proper torque specs and procedure when installing the new headers. At this point everything was left loose for adjustment purposes.



Drivers side went in easier than the passenger side. On both sides I needed to remove the motor mount bolts and slightly raise the motor to get the headers past the frame rails. Really easy to do. Here's the passenger side with the valve covers back on.



At this point I went ahead and torqued everything to the head and started working down stream, first with the collectors and the rear O2's. I grabbed a couple O2 block offs from the exhaust shop I used and used some loctite to secure them in the collector as they can come loose.



Anti fowlers are welded into the M&M's from the factory so all you need to do is screw your rear O2's in and it won't throw any codes.

this is the process you will need to go through for other header brands that don't weld in antifowlers from the factory.
Next I rigged up the rear O2's via a trick from Andres (345's Spinnin, Thanks Buddy for your help). I secured the rear O2's up and out of the way and used spark plug anti-fowlers to insulate them to not only protect them, but also to allow them to properly heat making the system "ready" so it wouldn't throw any codes, and still pass emissions. The rear O2's read plenty of oxygen in the outside air so the system thinks everything is great. So far so good, it works great! You have to drill out a significant portion out of the end to get them to accept the O2 but it works.

[FLATOUT]

After bolting up the collectors I moved on to the turnout pipes. These are supplied basically to cut to length for the customer. As with all things measure twice and cut once, or in my case do this a million times because your afraid to remove to much lol. I would simply mark the turnout where I wanted the cut, mark it, then mask it and cut it with a sawzall. The sawzall worked well even with the jet hot coating being so hard. After each cut I would de-burr it with the grinder or dremel and test fit.







After that get everything tightened up with the supplied hardware and your done! I took the time to really insulate and or wrap anything that I thought might possibly get to hot with reflective heat tape. I also ordered a set of Koolsox (same as the ACRX wire boot covers minus the word "Viper") through Koolmat.com.

Here's the finished install!





I put a few heat cycles on everything and went over all of the fasteners again. I also decided to move the passenger side O2 wire back and away from the rear passenger side primary just to be safe, there's plenty of room to tap the frame rail and install a nice hoseclamp out of the way.

***Lastly pay attention to any and all wiring that might come in contact with the primaries or collectors and insulate them from heat as necessary.***
Andy Wheeler

[FLATOUT]

Guys if you have any questions about doing this install feel free to PM me. I put roughly 10,000 miles on these post install and they were great.

One last thing to add to the install doc is to retorque everything after a heat cycle and then maybe again after a few more just to make sure everything is staying tight and properly fastened.

Andy

[plumcrazy]

nice job andy

[SNKEBIT]

I would not suggest the copper gaskets on the flanges. We have had the flanges warp from the copper squishing at the bolts, then the heating cycle warps them. We just use some high temp RTV. All of our headers already come with the anti-fouler in the collector, no need to buy more.
Unless that set didn't have them...........................just a little more info.
I also do a lot of hose and wire rerouting on the earlier gen.3's. I have found the battery hot wire laying on the exhaust shield melting from the factory....

[ViperTony]

Nice write up/install Andy. As SNKEBIT mentioned...those copper gaskets may cause a problem. I installed these on my Belanger system years ago and the flanges warped. I've since only use RTV and no issues in 5 years. But great write up! Thanks!

[FLATOUT]

No problem guys I will remove that from the install and update with RTV.

Also Mitch I did similar relocations of some of the wiring as well as wrapping lines in heat protecting tape or fabric just didn't notate it, I'll add that as well.

Also added the antifowlers before noticing there were already some welded into the M&M's, I will leave that in the install just so people can see what it is and how it's done for other brands that don't supply those from the factory.


Thanks guys.

[FLATOUT]

Updated Mitch.

[SNKEBIT]

Nice!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Dan Cragin]

Nice install, one other suggestion, when using those stainless ARP header bolts, always put anti-seize on the threads or they tend to seize up if you ever have to remove them.

[FLATOUT]

Nice install, one other suggestion, when using those stainless ARP header bolts, always put anti-seize on the threads or they tend to seize up if you ever have to remove them.

I did, and I listed it in the first post. That being said DUDES put some anti seize on those flange bolts.

Thanks Dan and Mitch for helping with the details, it makes for a better and lasting document.

[Westxsrt10]

How long did you let the High Temp RTV set up before bolt up?
I couldn't get the RTV to stop the leaks in the Belangers flanges on my 08. I had to use full face dead soft copper gaskets then cut them up to make a 'ring' type gasket.

[FLATOUT]

How long did you let the High Temp RTV set up before bolt up?
I couldn't get the RTV to stop the leaks in the Belangers flanges on my 08. I had to use full face dead soft copper gaskets then cut them up to make a 'ring' type gasket.

Hopefully Mitch and Dan can answer this one I used the copper gaskets, but it sounds like they recommend the RTV.

Guys any feedback on this question?

[SNKEBIT]

Don't let it set up. I put them together wet. It only needs to fill very minor imperfections. Never had an issue on ALOT of sets. The only leaks I have seen are caused by someone using ANY kind of gasket or bolts coming loose and falling out.