Hello fellow forum users. I usually do not have a lot to say but I do appreciate the information and sharing that goes on here. I am in a position to give a description of my recent and ongoing experience with Renntech here in Stuart FL as it pertains to their bolt-ons, tunes and service for our beloved w204s. I know a LOT of people are curious about Renntech stuff, whether it is worth the money, are their numbers and tunes conservative, etc. In fact I had all of those questions when I bought my low mileage 507 last year (4700 miles at purchase, 5700 miles now). These are the details as honestly and accurately as I can relate them. Feel free to message with any specific questions, I will answer if I can.

These are the pros and cons of my experience in full detail and transparency so enthusiasts may add more knowledge to the database of our platform..

Why I chose Renntech:
1) they are 7 miles away, much much closer that any other amg specialist
2) I HATE sloppy, mediocre mechanic work, when I pay performance labor prices I expect attention to detail beyond what I am capable of myself and they seemed to have that reputation
3) I believed them to have among the highest quality parts in the sector, which is what i was looking to put on the 507 and the idea of using one company's parts was appealing to minimize issues between parts and pieces. the huge markup compared to competitors products made me pause pretty much every step of the way.
Current state of things with my 507:
(I also went through a brief period with renntech R1 perf package installed if anyone has questions about that, it was barely noticeable on the 507 which is already tuned up from factory, but it had their HHT and cf airboxes which were part of all their higher packages too so I figured I would try it)
Power mods: renntech cf airbox, renntech 82mm throttle bodies, renntech longtube headers (coated), renntech downpipes with 200 cell cats (coated), renntech R3 tune.
other mods: renntech brake perf pkg (lines, race fluid, fr pads), renntech cf strut braces front and rear, RW carbon rear diffuser, set of Signature sv103 forged wheels 235/19 r888 front, 265/19 r888 rear for racing/track

The car made 480.5whp/430.5wtq on renntech's dynojet 93 oct pump gas. It feels strong.

Renntech uses 17% driveline loss value in their calculations. That puts my car at 579hp/519tq crank numbers by renntech's own calculations.
The numbers on their website and the numbers represented to me for crank hp before the purchase was 575hp/543tq for the R3 tune including the air intake and exhaust parts they installed. As you see my car with less than 5k mileage made 24ftlbs less crank, or 20+ftlbs less wheel torque than advertised. My torque value barely rose to the level of their advertised R2 package which had the MUCH less expensive headers in that package. The explanation from the owner, Hartmut, was that cars differ, with not a single attempt to explain further or check parts on my car versus the car they got the advertising numbers from, or to explain if cars regularly differ by more that the difference between their R2 and R3 packages. Obviously being that far from their advertised torque value after buying 'all the right parts' was disappointing and was the beginning of a few more issues to follow.
I did NOT get the transmission upgrade or the LSD upgrade listed as part of their R3 package, so my cost was not the full advertised R3 cost on their website. I was told my trans would be fine without the upgrade and that my car had lsd from factory (I guess they assumed all 507s had one, wrong). Renntech agreed neither of those things would affect a higher gear dyno pull number by any significant amount.

I will say that I don't see other c63s on 93 pump with similar mods making 450wtq or higher,, but for some reason renntech advertises 543 crank tq value for R3 with my parts.

After the R3 tune was put on, the check engine light would come on anytime I played on the car hard. I took it back to them and they said they forgot to disable the cat eff. software, so they 'checked that box on the tune' and sent me home. Check engine light still kept coming on everytime I would run the car for a bit. I would check the codes and it was always cat efficiency codes. So I took it back to them a second time after the tune and they 'deleted the cat software'. So far (50miles later) no check engine light, so that issue may now be fixed, hopefully.
A couple weeks after they fixed the CEL issue with the tune, I noticed a scuff mark on the top of the expensive cf airbox, it appeared to be hitting the bottom of their cf strut tower brace, even though there was a good bit of visible space between them. I wondered if it could be engine mounts, but with only 5700 miles on car that seemed unlikely. Turns out the seal failed on their cf airboxes, after less than 1000 miles, allowing air in, and causing the airbox to lift under throttle. They did not replace the airbox, they touched up the cosmetic damage with clear coat, repaired the seal, and put it back on my car. The damaged area is small, but I now have a 'blemished' $2400 airbox due to no fault of my own. They also did NOT bother to check the cf strut brace that the airbox was hitting into, I had to tell them to take it off, inspect it and repair or replace it if it was damaged. It had cosmetic damage also that they brushed a bit of clearcoat over. I mean these are expensive cf parts that are constantly exposed to engine heat, any chance these damaged areas become problematic years down the road?

I had the data card checked on this forum after they told me the car had factory lsd and the option was not listed, so while they repaired the clearcoat yesterday, I had them do the tire spin test for lsd, car does NOT have lsd as their salesman previously told me.

And that brings you all up to date as of yesterday.

The mechanics there are great, and do good work, the salesman is well-meaning but has been incorrect on a couple issues, the owner is an ego who offered no actual information when questioned about why his R3 tune did not live up to its advertising.

The car feels very strong, quiets down very well in Comfort mode, and the headers even though crazy expensive, sound better to me than any others I have heard. With stock resonators, secondary cats and mufflers the car is nice and quiet in C, but awesome sounding in S+ and M, without all the noise of the cat and resonator delete cars, those cars always sound broken to me.

The car feels fine, BUT does not have any perceptible advantage over similar nore affordable setups...Renntech's advertised advantage was the 20 extra ftlbs which never materialised

I am sure they are great for the newest models, but in terms of w204 they refuse to try e85 flex, they refuse to install any other lsd than their own $3200 unit, so they seem to have given up on w204s other than their tunes from the era and exhaust and carbon parts which are the most expensive in the market.

I will have to decide whether to continue there, as I do like my mechanic. I have already gotten several private messages just from my single reference to renntech in another post, so there seem to be plenty of w204 guys considering their stuff. Happy to answer any questions the best I can.

 

I wouldn't worry as those numbers are really good. You could try new spark plugs or delete the second cats if those are still installed.

Could be your car is not broken in yet and just needs to have a few more miles on it.

Gas can also make a difference also. Do you have the dyno graph ?

 

Hate to say it but as far as pushing the car further, I’d say your stuck if you plan on sticking with Renntech.

in terms of the upgrades you did I’d say for 480whp and 430wtq... the renntech box and tb upgrades on this car are a complete waste of money.

Renntech headers are absurd for 8k... and they aren’t even long tubes. I’d get rid of your secondary cats after the o2’s. Those free up 10 hp 10tq. Resonator and stock mufflers flow up too 800whp...

e85 kits work good. 20 whp 20 wtq peak. 30+ in mid range.

Your other choice is eurocharged Orlando. And I know the owner.

 

It would be easier to not worry about those numbers if the 'torque' that was missing wasn't the thing that separated the renntech r3 tune from other tunes when i was deciding what to go with lol..

I appreciate the response.

 

ya there is a eurocharged close by with similar mods to mine, trying to get him to race so we can find out if those things 'make no difference' and if other companies are actually faster, he seems to be stalling


BTW I haven't heard only good things about eurocharged either

 

all the tunes are similar. You can only do so much on a N/a car.

id delete your sec cats. And unplug battery overnight. That should free up some HP and reset all adaptations.

eurocharged is ok... only if you Dyno tune your car there. Mail order tunes suck. If you wanna go further than what your car is making you need to consider a different shop.

 

Their headers are the best part but the price compared to other lth is crazy, think about it,, you say they aren't even long tube but they make same power as ones you say are.. they take up a lot less space than other lth which has advantages,, and the coating helps noticeably with undr hood temps. my car seems to make similar power to and sound better than(for my preference) other cars with lth even though they usually have 2nd cat and res delete, etc and my underhoid temps seem well managed with the coating and 507 vents but doesn't change the fact that renntech didn't come close to their own tq value claims. I think the airbox and tbs are more suspect than the pimp.but expensive headers, imho.

Might consider e85 at some point, but would likely have to get soundly beaten by a flex fuel car before i pull the trigger and scrap the renntech tuning.

Orlando is 3hr drive at least

 

Gas can also make a difference also. Do you have the dyno graph ?[/QUOTE]
Here's the graph, 5 back to back pulls

 

Here's the graph, 5 back to back pulls all within ~4hp/tq

[/QUOTE]
this graph looks like what a normal c63 does with Mbh or arh longtubes, row’s/filters and good tune. So yes for what you paid for and what you received isn’t exactly ideal. then add e85 and you’ll be close to 500 whp and 445-450 wtq. That’s as much as you’ll get out of this car n/a. If you want more you need nitrous or a blower.

 

makes it seem odd that renntech advertises 543tq (450wtq) on 93 oct then with their r3 huh?

 

still had coilovers and lsd left to do but will have to consider whether to continue with renntech, as they already say they won't install any diff other than their own, not even a mb lsd and their kw coilover setup is like 3x more expensive than others i have seen

 

If you're trying to walk a "fake" engine HP/TQ number back to equate to your acual dyno numbers you are doing yourself a disservice. Unless they have have an engine dyno in-house those numbers are made up and meaningless, only used to sell to people that don't understand horsepower at the wheels. I wouldn't be concerned about your power unless you can compare to multiple other c63's with their r3 package and you are considerably down on power in comparison. At 480whp you are fine.

Some cam adjustments and timing changes between 3500-4500 rpm could easily change things, but I'm guessing that they didnt even dyno tune your car on-site and just loaded up a generic canned tune? For what you paid it should be tuned on the dyno to extract all the available power. Canned tunes work better on newer cars with more advanced ecu/knock control systems where they run off the oem wideband and knock sensors all the time (new m3/m4 as example). In those cases a canned tune can be run really aggressively and will try to make the maximum power all the time and very quickly pull power down as knock is detected.

 

they have 2 chassis dynos in house, not sure if they have engine dyno, they might. and the 'fake crank numbers are there because that is what THEY advertise with and therefore its the only way to compare their claim to my reality. I also think that wiggle room in the translation is why they advertise with 'fake' crank numbers, not because anything about it is difficult to understand, imho.

 

I appreciate those ideas you related,, they didn't tune the car on the dyno, they just loaded their r3 tune that they say is proprietary to their set of parts and then dyno tested the car. I was hoping for over $20k spent (all mods not just power) to get a bit more personal tweaking on the car also, but wasn't sure how much gains were there without syveks or custom tunable platform.
perhaps one of you guys who knows the tuning side can explain more to me about what can and can't be done with their HHT and tune. I am just a dumb chassis guy, lol

 

Get your money back and get a weistec stage 3 with long tubes all in 15k and you’ll have 800hp

 

15k include trans upgrade and labor?

"Get your money back" what world do you live in where this happens lol?
if it was a hp race or if I wanted boost I would have kept my vette. I want best n.a. perf in this car without hurting any streetability. Some of your comments are helpful and some well....not as much

 

I'm willing to bet your car drives like it came with this power from mercedes.

You can go try v69 on a different tuner and you will make 5whp more and 8fts more but your car will drive like ****.

Go put some shell 93 oct and drive the car for a week and re dyno it after it adapts. Im willing to bet it will make more power.

 

Interesting I appreciate that, yes it drives very well and other than the issues above I like it a lot. Every once in a while the throttle response in 1st gear starts 'bucking if you aren't really smooth with the pedal. As stated in OP I am presenting both what I like and what was disappointing in this thread so others may have more overall knowledge of our platform. They did dyno it 3 times the morning before i arrived when I was not there (although they said I would be there for initial dyno pulls they did not live up to that), and I had assumed those pulls might have been for it to adapt.

I wonder why i wouldn't have gotten simple suggestions like that, or even the time to explain such, from the owner of a company that has over 20k of my cash?

 

Pretty sure renntech would take care of you after spending that much money. A customer at knauz spent 20k on his cls55 back in the day with kleemann and wasn’t making the advertised power. He took everything off and they refunded him and he went in a different direction.

the owner of renntech is a jag off know it all. Don’t expect him to explain why the car isn’t performing as advertised. He’ll likely blame your car.

sad to say the car isn’t performing better than just cheap header from vrp and row airbox...

 

Lol, u r very optimistic

Why don't you bring that cheap header, row airbox car down and we can find out if its variances in dynos or if your cars live up also? Willing to put mine up for a 40 roll.

 

He is right though. i think your xar would make the numbers you wanted with different headers on the car.

I'm also running the r3 fiile but not there headers.

If it makes you feel better i just got there tuning but parting the car for an amg gts lol

 

And how different are your numbers than mine? Stock from primary cats back?
not sure they will buy their headers back

You are saying cheaper lth will gain me 20wtq without hp loss of more than 4hp?
I Like the idea of that, but only if I get my header money back from renntech lol

They also claim their R3 tune is proprietary to their own hard parts, so its odd that it would be optimized by a different header design no?

Racing may be the only way to figure out if cheaper is better, as long as theirs runs as nicely also.

I havent heard one other person say 543tq crank advertised value from renntech on 93 oct seems awfully high as that equates to 450wtq by their own drivetrain loss calculations, but thats still how I feel. I would like to see the car with same parts that put down that number, I am betting they used number from a more or differently modified car than the parts list they use for R3, as they also make an x-pipe they claim makes power/tq that isn't included in R3.

Also everyone would be ok with brush on clearcoat repair of the cosmetic damage on the cf underhood parts? Thx

 

Mbh headers, rows with paper filter, e85 tune.

Mbh headers. Stock airbox. 91 oct. tune.

 

Peter, I have seen similar dyno charts.. but tunes are more than peak numbers thats why i would be interested in racing to see if other things affect real world perf other than peak power number. I like those e85 numbers but would want to ride in one tuned that way to see how quality the tune is other than on the dyno.
anyway hopefully there is some info in all this that others find helpful.

I love racing other c63s so if anyone is ever in FL let's hook em up for posterity.

 

The guy has a $20k tune and headers and wants to race everyone now. Cute.