I've read through the old threads debating whether Weistech or Renntech is better for a tune. All I can find are older threads talking about either brand for tuning Benz models other than my own. 2019 GTC 1,400 miles. 93 Octane fuel.
From what I've read, both brands have had their ups and downs over the years concerning price, warranty, and power but Renntech's customer service hasn't ever been questioned yet (to my knowledge) (I also looked at EuroCharged, but no info on their site about a GTC tune)

The old threads say that in general, Weistech offers a more powerful tune but can have spotty customer service and potentially warranty issues compared to Renntech.
In communication with both brands via email their current prices are nearly identical.
But their advertised gains are not. Weistech's advertised gains are currently explained in a more straightforward way to understand because they are just giving you the projected gains without any discussion of factory recorded base numbers vs internally recorded base numbers. Renntech's advertised projected gains are harder to understand and supposedly based on starting figures higher than the factory. Renntech's current calculation is convoluted and not straight forward in my opinion.

Renntech is advertising total gains of +84HP/93TQ with no catless downpipes but their marketing materials make it harder to decipher what the true projected gains will be. The factory stock numbers are -25HP/19TQ less than what they have claimed to record as their stock baseline. I could easily believe that.

Weistech is advertising +60HP/122TQ with no catless downpipes.

If you add Renntech's projected gains or projected gains (less the difference from the factory numbers) you end up with a range for projected HP gains of 609HP-659HP, but Weistech still is the highest for TQ in any calculation.

I haven't been able to find any current threads with up to date info on which of these tuners will be best for me. Or any threads to sort out the Renntech calculation issue.

Has anyone had an experience recently with either brand for a GTC tune? If so, I'd love to hear your thoughts.

 

There are dozens of threads regarding tunes, and assuming you have read most, you will notice that Weistech is rarely ( if at all) mentioned and renntech and Eurocharged are probably the most common and reliable tunes that people end up using. This is because there are very few problems and both companies have a really good understanding of the 4.0.

i’ll just say this about tunes. Don’t get hung up on peak horsepower and torque, as you will not notice 15 or 20 hp or torque. The real advantages are the throttle response which transforms the car.

 

I was in the same place as you a month ago and combed through all those threads as well. I ended up going with Renntech primarily due to that I hadn't found any reports of the tune malfunctioning, while I had seem some on the Eurocharged side. It looks like Eurocharged did rectify the issues but I recently went through about a year of tuning headaches with my old 515whp/530wtq BMW 335i and wanted as seamless an experience as possible. Renntech seems to be extremely reliable, so I decided paying the premium was worth it. The rep I was interacting with has been extremely responsive, knowledgeable, and a pleasure to work with.

Power-wise, I don't find Renntech's calculation convoluted at all. They are just saying that the stock car actually makes more peak power than the number MB advertises, because MB doesn't report peak power but instead uses average horsepower. Since Renntech and other tuners report on peak power, there needs to be an adjustment for accuracy's sake. I would imagine the 2 tunes produce about the same amount of power. The Eurocharged sales rep sent me this:

I honestly don't think you can go wrong either way - both of them will put you around 600/600 peak bhp/tq. The car was very noticeably transformed by the tune into the beast it was meant to be and certainly feels as powerful as my old ~600/600 bhp/tq 335i (but obviously exceeds it in every other dimension )

 

I went with EC over Renntech, but I'm not someone who likes paying double for the same thing. I've had no issues with my tune, and I run my car hard. I've put 8k miles on it since tuning.

 

Enter VRP...

We offer AMG parts without AMG tax. Here is the dyno sheet for a GTS we did recently with our stage 1 turbos and tune.

Shoot us an email if youd like to know more. Info@vrpspeed.com

 

I agree with Hetzle. Renntech has clearer info about HP and TQ. It really doesn't matter what is your initial (stock) HP/TQ, what matters is the gain. The best way to look at it is by reviewing a Dyno graphs (see elow), showing Stock/Tune comparison, something that Renntech provide and others do not.
I have a 2020 AMG GTC and just tuned it with the Renntech HHT. Although I have to admit that it is difficult to "feel" a 15% increase in HP/TQ in a 550HP car, I did find it a bit quicker and more responsive to achieve top speeds while in 5th/6th gear and north of 5000 rpm. While playing up and down the 4/5/6th gears at 5000-6000 rpm range, it becomes a real "beast".
as for 0-60 or top speed, I could not see improvements over the stock tune.

 

OP here.

Thank you to everyone who responded. This was really helpful.

I did end up going with Renntech after reading though these and also speaking with them.

I'm having the stock gtc dynoed Friday. I'll post the before and after results through each stage.

Stage 1 ECU HTT and air filters.

Stage 2 Turbos, injectors, and catless pipes

Stage 3 An on-dyno tune.

Anything I'm missing from the stages?

 

Fantastic! Definitely post up your results between the Stock and Stage 1 implementation. It will be interesting to see another iteration of what the GTC puts down in stock form.

-Chris

 

I'm a little confused here.

All of the specs are quoting GTS cars, but the OP said he had a GTC which starts at 550 hp (and always dynos more than...). It's all the M178 motor - are their material differences in the cams or turbos in the GTC variant that would allow for better performance in the tune? These dynos all stat their new ratings around where the GTC begins. I thought it was only the GTR that had different turbos -

Id love to be wrong because I have a new GTC and I was looking at the Weistec numbers showing 160/180 in gains and scratching my head trying to figure out how they do that with an ECM tune alone (200/300 with downpipes!).

 

OP again

I had the exact same question originally. I summed it up to the possibility that gt/gts are more common and therefore are the majority of the advertisements by tuners.

My additional understanding is that the gtc is basically the gtr minus a cooling function and 9 stage traction control.

I'm throwing a dart here but I'd say even with the same motor the gtc will have more power than a gt/gts due to...

idk why. Maybe someone can chime in.

 

Has the identical motor to the GTR except the boost is turned down a few psi. The other GTR differences are the added front downforce panel under the front bumper and wider wheels up front. The exterior differences are obvious. As an aside I might suggest waking up the car with a sprint booster or the like. Makes a huge difference without altering anything warranty wise.

 

The engines are the same on all 4 (GT\GTS\GTC\GTR) but tune differently. If you are looking to tune up a GT or GTS, be aware that you don't have the mechanics and safety to handle the extra HP/TQ. Front Break Rotors are 14.2 instead of 15.4" . Narrower rear tires and track. Mechanical Rear differential and no rear steering. Ride control is higher. Unless you change all these, boosting the HP/QT too high will not yield meaningful results on real roads and risk stability and breaking abilities.

 

GTC and GTR share the same engine with different turbos and similar final drive ratios. The GTR has more boost

 

MB advertises the GTC to make 550hp.

It really makes around 600hp.

A tuned one makes close to 700hp.

If you are disingenuous in your marketing, you can claim an increase from 550-700 with your tune.

 

Now I understand how Renntech does such good business. They're great at marketing to people that have read a couple of car magazines.

 

This answer doesn't smell right but very well could be true. You could debate the safety spec but focusing on the M178 only, if it is correct, the tunes are hardly worth it for a GTC or GTR. Getting 20HP gains for $3,000 is a waste-o-money. There has to be more to the story for GTR and GTC owners. And, if there isnt, that might explain why its never spec'd out separately.

OP don't waste your money before you have that conversation - please update us on what you find. I can find where the information quoted about its scraped but nothing that specifically states that all variants are the same except the factory tune specs...the GTR has a different exhaust but that wouldn't mean all that much in terms of specs. From personal experience, I had a C63S a year ago and ran into this looking at tunes between it and the C63 - in that case it was a 'save your money' moment. The S was really a simple factory tune and the gains were all about the non-S getting that upgrade.

 

It doesnt really matter but usually stages refers to

1: tune alone
2; bolt on modifications such as exhaust/downpipes and tune
3: turbos and retune

 

This is incorrect.

A C63S/GTR/GTC will also pick up a decent amount of power with a tune. It might not pick up as much as the base model C63 or GT but there's still a significant gain.

 

This is EXACTLY what I had thought too, but for the life of me I cant find a single spec of information to validate it....and as Abe Lincoln used to say....

PS - man I hope youre right!

 

I think you're missing the point to prove your own.

If the tune is the same tune for a GTS and the GTC and the cost is $3,000 the GT jumps from 480 to 600, but the GTC jumps from 580 to 600 the GTC. The GTC owner can think twice about the value of that tune as compared to the GTS owner who says "hell yes!"

 

There's a dyno plot of a GTC in this thread showing a 85 hp gain from a tune.

A GTs, C63S, GTR, GTC all pick up major hp from a tune.

Yes a base GT or C63 pick up even more because MB neutered those cars from the factory. But the difference is something like 80 vs 120. Not 20 vs 120.

 

We're talking past each other. Before we continue to debate the merits of the tunes without the underlying factors, let's get the feedback on the turbos locked in.

 

Pretty much all factory turbocharged cars will pick up fairly significant power with a tune. This is true from a VW Golf to a Ferrari or McLaren.

Pretty much all established aftermarket tunes are 95%+ identical. You can pick the one whose website you like or who answers your email first or who is located closer to you. If you think you'll get more kudos on the golf course mentioning you have a Renntech tune, by all means go ahead and get their tune.

 

are we?

this is wrong. im trying to prevent you from spreading misinformation and confusing people.

 

Clearly you are the guy that has to be right...and yes, it would appear we are.

here is a summary of what I said - the tune isn't as much benefit for a GTC and I'm not sure on paying full price for the tune which markets itself on base model specs that the GTC isnt
you appeared to say - there is benefit with both cars because there is a nice boost in both cases, the base model being higher benefactor but sizable gains for both.

Since both things can be true, yes, Id say that's called talking past each other. If I am correct in what you are trying to say, I FULLY understand what you are throwing down. What we wrapping around the axle on is the value - I can appreciate that you see lots of benefit for your bucks. Im sitting with a GTC wondering if I want to do this tune first or spend on something else - and the literature simply isn't clear on the gains; especially with the specs still showing some degree of debate.