I’ve been wondering if there’s any mods that you could do too a gl?Have any of you guys modded your gl’s?

 

For me (2013 GL450) I did the second row headrest mod because I have kids sitting there often. Some people have adjusted the ride height (lowered or raised) by modding the sensors for the airmatic. I put in the aftermarket air intake hoses to replace the originals that fall apart, but my aftermarket hoses also fell apart after a few years due to the heat from the turbo. I run slightly larger diameter tires, they only rub a tiny bit if you hit a bump while turning sharply, the larger size is cheaper. I have aftermarket wheels for my winter tires, they have a different offset so they stick out a little bit, which I think looks good. Mostly I spend all my money on repairs, I don't have much left for mods.

 

2015 GL 550
Renntech Stage 1 Tune
Panamericana Grille. All black to match Gl 550 mesh looking parts
Black star (was already illuminated)
Aftermarket Xtrons head unit.
Wireless charging (waiting on that part to arrive).
Clip on wood grain for the steering wheel to match the rest of the wood grain.

 

How do you like the Renntech tune and is the power gain noticeable?

 

If I'm being honest, I first tuned my S550 Coupe (C217). When I say it will blow your mind, my guy it's night and day. I literally blast cars out of the water daily. It's ridiculous.

That said, I have a 2015 GL550 same M278. It has 102K so I didn't want to spend $2500 on a Renntech. I found a tuner highly rated likely from this forum who remoted in and did the tune. I'm a Technology professional so I watched him. He copied some files likely from some underground website for tuners and my truck ran worse!

I figured Renntech did me good in the coupe with 30K miles. I will try them. Paid another $2500 against my better judgement. I will say the tune is noticeable. My truck doesn't run worse it feels better. But the gains just aren't there for $2500. My GL 550 would smoke people anyway, but I thought the tune would really take it to the next level like my S550 Coupe. I was hesitant but I put my faith in Renntech anyway. You will notice a difference just not significant given the weight and in my case age/mileage if the vehicle.

Yes the truck is quicker. Everything went smoothly. My truck is up-to-date on all Mercedes maintenance. The gains are O.K. But not $2500 worth. I knew it wouldn't haul *** like the coupe but I was left disappointed. The short is I wouldn't recommend the Renntech tune for the GL.

The cost is too much for what you get. That said I do have 102K mileage. But my truck is maintained all services done. What made me the most happy? Changing the spark plugs and coils and being completely amazed at the gas mileage I got. My truck drank gas prior and I literally changed the spark plugs (and coils) and the gas mileage was amazing. I tend to keep my cars for 2 years max (the non-kid hauler) then trade them low miles and good value. So changing spark plugs for me wasn't something I really came across. That said, damn the difference was immediately noticeable when tracking gas.

I also found the air intake hose was torn (common issue) which could have contributed to the robbing of my gas mileage. Pop your hood and check. You'd be surprised.
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Thanks for the detailed write up. I purchased my 2015 GL550 3 months ago and was considering a tune. After driving it I really don't see a need for more power as it has plenty for what I need. I will say, this is the nicest SUV I've ever owned. I previously had an ML550 and the interior is a night and day upgrade. That said, my wife has a 2011 Camaro SS that I've tuned, headers, etc and is a fun muscle car to drive, is fast, and sounds great. She's pretty much taken over my GL550 because the interior is so comfortable and she loves the driving safety features. I plan on looking for an S-Class coupe next year to replace her car to maybe get her out of my GL. The S550s between 2015-2017 look nice and I've looked at some S63s online. The 2018 S63 looks like a beast but I really think the 63s would be overkill for what we need. It's good to hear you saying the a tune on an S550 Coupe is a huge upgrade. That should give us enough power along with the comfort of an S-Class. That's more than likely the route we will go. The one option I'll have to search for is the upgraded stereo. I have the upgraded Bang and Olufsen in my GL550 and we both love it.

 

The tune is TOTALLY worth it on the S Class Coupe. I only did the stage 1 at that.

 

Below are the mods I have done so far:
1. Replaced Halogen headlight bulbs w LED for better night time visibility
2. Replaced Front Grill to remove the "Mom" look

3. Installed ScanGaugeII to monitor DPF & DEF levels.

4. Added Hitch Step to easily reach cargo when 3rd row seats are folded.
5. She inherited the roof bars & cargo box from my totalled X164 GL350 for my family of 6's driving vacations.

 

What headrest mod are you talking about ?

 

Can you give me the link for the aftermarket intake hoses?

 

The headrest mod is for the Power 2nd row Easy Entry seats. The headrests automatically drop down during the folding operation. However, to allow this automatic drop-down, they are angled way too far forward making it very uncomfortable for people sitting in the second row. So the mod is the remove a metal pin that holds them at that bad angle. The tradeoff is that you have to manually lower the headrests before using the power fold operation, otherwise they sometimes don't drop properly and will hit the back of the front seat. To me, the tradeoff was worth it, my teenage kids don't mind manually lowering and raising the headrests occasionally in exchange for the comfort on every trip. The good pictures are way down in post #243 in this thread:
https://mbworld.org/forums/gl-class-...adrest-10.html
There are other threads as well, just search in the forum.

The intake hose is from Autozone or Amazon, it's the Spectre Air Intake Hose #8741, just two flexible rubber couplers and a flex hose. You cut the hose shorter. See post #13 in this thread
https://mbworld.org/forums/gl-class-...ntake-arm.html
Note that I've had to replace one of mine again already, they lasted three years, the heat from the turbo will eventually degrade the plastic flex tube and it cracks. So it's not better than the Mercedes hose, it's just cheaper. Spectre does make a flexible metal hose, that might last longer but it's more expensive and harder to find.

 

I can help you with the RENNtech tune, DM me if you need anything.

 

Here's the hose I used to replace the original ones on my 2015 GL350.
I was worried that they might come off, so I also used some stainless steel zip ties to help clamp them on. I've had them on for about 1.5 years without having to mess with them.

Jeff

 

Catless downpipes, tuned and elec exhaust cutouts.
Sprint Booster for better throttle response
lowering links
12”sub
blacked out the chrome trim
debadged
Osram CBB bulbs
blacked out center grill
550 tips and diffuser swapped for 63 tips/diffuser

Video here and others

 

I have a 2013 GL450. I tuned it I believe with the OE Tuning setup which I want to say was $1500 with the interface box. It’s probably the best money I’ve spent. The GL450’s M278 is just a detuned version of the GL550’s. So if you have a 550 the difference might not be noticeable but ok mine it’s borderline absurd.

Other than that, it’s just maintenance stuff. Pretty much all high mileage X166’s have bad engine mounts and turbo coolant lines. So I did all those. Upper and lower control arms, tie-rod ends, ball joints, powerstop rotors and Z23 pads. I also added the cam sensor fuse wires as well as the updates sensors and actuators.

Today I put on GL63 wheels and a set of pilot sport tires.

Maintenance makes all the difference in the world. I went to go buy a GL63 the other day and walked away because it was slower than my 450, had completely blown engine mounts, pulled to
the side while accelerating, etc. It was rough.

My GL has active curve control, which makes all the difference on these cars and is otherwise fully loaded other than B&O. So I kept it and decided against the 63.

 

Lucky to see active curve on a 450!!! We searched for months for a 550 with it. Crazy to see some optioned lit crazy and they just skip the best option for the car. Makes it handle like a small car that can still take curves. Wife loves it and is a section she can clear 80mph while my little Chevy Volt I daily struggles at 70mph let alone the G we have as 55-60. Ahaha.

 

Active curve works well in the GL. Makes a huge difference in handling.

 

Agreed, we picked up a 2015 GL550 a couple months ago that had active curve along with the B&O system. Both are great options.

 

I think it’s because a lot of these were leased and it’s hard to sell this option on a lease since so many people are shopping on price. So few people know what it is too. It’s a hard sell unless you know what it is and how it works. Or if you’ve driven an X166 without it and then with. Then it becomes the easiest sale ever.

 

I used to have that on my Jeep and it made a big difference, but debating if it's needed with my GL.
How was the installation? Diy friendly? Are you satisfied with the throttle performance now or do you think you can survive without it?