Hi All,

I've been staring at these LTH's long enough and finally have some time to plan the install next week. I just wanted to verify a few things with people who may have done this before:
1. I'll be doing new exhaust gaskets, studs and bolts...are the standard SL55 part numbers fine for this?
2. I'll likely pull the coil packs and wires to have as much room above. Any recommendations for pulling stuff for better access below? I'll likely be on a lift but there's a chance I may not be.
3. The headers come with a bolt-on ovalized adapter piece for tying the headers into the existing system. Any recommendations on how to get that installed, meaning does the entire exhaust system need to come out to get that piece welded on? Is the existing system stainless?
4. Any other maintenance/RNR that I should do while the manifolds are off before the headers go in?

As always, Thanks!

 

replace the engine mounts. for the best weld job the entire rear section will need to come out. you may want to consider having the resonators removed at the same time. use the special offset wrench to remove the plug wires makes things much easier

 

If the resonators are removed the sound may be too loud and it's possible you'll hear drone. I left mine in but had the primary cats remove, perfect cruise sound levels, no drone and sounds wicked at WOT

 

I’m yet to hear anyone say there’s drone after removing the resonators. I’m having mine removed right now

 

I had to put resonators back in after adding the eisenmann race mufflers. Way too loud and too much drone for me

 

Maybe I should have specified anyone that leaves the factory mufflers on hasn’t had any drone issues even with headers and removing secondary cats

 

I have LTH no cats or res, sl63 mufflers no drone sounds like a animal

 

My plan is to get a 3" 304 SS straight back to the factory mufflers w/ a new crossover, eventually. Right now I just need to tie into the existing system.

Thanks for the reco on motor mounts, definitely seems like the time to do them

 

Leave one set of cats on with stock or aftermarket mufflers and you'll have no drone and wont be obnoxious loud. Also the existing piping isn't 3" so I'd drop the entire system to have it welded better. Lastly for sure try to do the motor mounts since you'll be in that far anyway.

 

Hi All,

Only a short 6mo later but I finally managed to get my lift installed, get parts squared away, and installed the LTH's over the holiday weekend. Here's a quick rundown of my experience for future use by anyone wanting to attempt. While it's not necessary....I HIGHLY recommend a lift to perform the work.

Tools:
-Everything that you have in 10mm 1/4" drive. I found my 10mm flex head ratcheting box end wrench invaluable: https://www.tekton.com/8-x-10-mm-fle...rench-wrn76103
-I found that a standard depth 10mm directly on a universal with however many extensions needed allowed me to get everything loose and I used the ratcheting box end to get them off faster.
-The sparkplug wrench from FCP made removal of the plug wires a snap: https://www.fcpeuro.com/products/mer...n-wrench-2771z
-I use a 16mm flex head ratcheting box end wrench instead of the motor mount tool.
-You'll need a way to cut the existing exhaust pipe....I used a 4.5" cutting wheel on my grider

Supplies:
-I basically grabbed the 8 gaskets/16 studs/16 copper nuts from this kit (part numbers are below the main picture and can be ordered separately): https://www.fcpeuro.com/products/mer...upplier-517651
-I did the Black Series Motor Mounts (I did not do the trans mount at this time as it was just as expensive as both the motor mounts): https://www.fcpeuro.com/products/mer...ercedes-538475

Tips:
-Disconnect the battery. The extensions used to access the nuts on the passenger side are danger close to the nut on the back of the alternator.
-I wasn't able to keep the existing heat shields on top of the motor mounts. I left the bottom bolts out so that I could lift and nudge the engine left/right to aid in header install. Driver side takes a little more nudge to the right than the passenger side. This is why you only put the bolt in the top of the motor mounts.
-I was told you don't need to disconnect the steering shaft, I did it. The piece attached to the firewall pushes into the cab (slow steady pressure), the actual shaft doesn't move up/down (TWSS)
-Removing the existing bolts and studs wasn't too bad. All the top bolts are easily accessible from the top with the airbox and plug wires/coils removed. The bottom bolts are accessed from the rear of the engine, except the front 2 on the passenger side and the front one on the driver side. you can get to those from around the steering rack. Almost all the studs came out with the bolts. I think i had 3 that didn't. I just installed 2 nuts and spun it out from the inside nut.
-I had a couple of the new studs have a hard time hand threading in, so I made a tap out of an existing stud and ran it down by hand...all was good after that.
-The MBH connector piece from the headers to the existing exhaust system is a TIGHT fit, and takes a little work to get it over....but it's a high quality piece.

I think the headers with the remaining factory system (secondary cats/resonators/mufflers) is perfect for me....just slightly more at idle and rolling around town than factory but sounds mean under full throttle. This also seemed to add a good bit more torque, according to the butt dyno (I already have an 83mm pulley/tune).

That's all I can think of.

 

Your butt dyno is accurate since these are guaranteed to add at least 40 hp to the wheels

 

I have MBH. 1. 7/8 headers and only stock mufflers I get low speed drone

 

I too have MBH 1.78 LT headers. Zero drone with primary cats removed, all else stock on exhaust.

 

i noticed a REAL small amount while backing out of my friends driveway yesterday but it was only within a 50rpm range

 

Hey I’ve got an 07’ E63 that I pretty much completely rebuilt and although the relative performance I’ve experienced with the “Shorty” headers has been pretty good, I’m left wanting more! But by more, I don’t mean Loud and Raspy, as many seem to go for. Since my existing OEM Exhaust is in great shape coupled with the fact I don’t plan on running a Turbo, which as many realize requires 3” pipes, I would like to retain as much of the existing exhaust as reasonably possible. I appreciate the description that these MBH Headers tied into the existing system sound relatively stock, with a little more at idle and appreciably more at throttle, but NOT obnoxiously so.

What I don’t quite understand is the statement that they “fit into the stock”? Sure the connector piece should allow for it to fit over the existing, only once they’re cut at the appropriate spot on the existing pipes right? I’m not sure where the existing pipes disconnect from the OEM Headers on the SL, but on the E63 the existing would have to be cut most likely significantly after the first set of Cats. As such, I would want to either re-use the Cats or get similar as installing Race Cats before standard OEM 2nd Cats would seem to be a waste of $$$ (Since the later would restrict the flow of the Race Cats). If one is doing it on their own, after cutting the existing to the proper length to join the Adaptor, one would have to determine whether or not to delete the first Cats or retain them and adjust accordingly. Moreover, since the Cats would be moved from their OEM position, one would have to get 02 Cable Extensions to tie into the OEM 02 Connectors. Ideally, one could do this while retaining the OEM Brackets which attach to the Exhaust Pipes on each side of the Tranny! I just haven’t seen an example of anyone actually attempting this. Rather the opposite where some allow for them to hang “freely” unsupported all the way back! Yikes!

 

6_Myles I am getting ready to do this job on my 2005 SL55, How did you connect the MBH extension to the existing exhaust piping? You mentioned tight fit, does it go over the existing pipe? I assumed it had to be butt welded.

Any pics?

 

I'll take some pictures this weekend, when it's on the lift. I haven't gotten mine welded yet, but they are a TIGHT friction fit. I am still trying to find someone locally who can do a larger exhaust system for the car so I haven't sweated it too much.