xtyper

I'm considering adding some downpipes to my car (haven't decided on catted vs catless), but don't really want to go through the hassle of getting the ECU re-tuned. So my question to you guys is, besides getting a CEL, what exactly am I giving up in terms of power and/or safety by not getting an updated tune? Also, considering my car is already running very strong tune-only, are the performance benefits of downpipes worth the time and money? Looking for real world experiences here, not some vague feedback like "I just installed some downpipes and now my car really flies!".

Thanks in advance!

Jshinone

I just installed some downpipes and my car really really flies!!!!!!!!!

Jshinone

Just kidding, I did some catless downpipes on my 2012 E and I did it with a tune at the same time. What I can tell you is that my tune was on the rich side at first when I put the downpipes in. My friend had a tune and stock exhaust and his tune was where you would expect it to be. We would run about even when we raced each other with these set-ups. I ended up sending my ECU to get the air/fuel fixed and then my car was significantly faster. With less than a quarter mile I would pull 2-3 cars on him. On the highway it wasn't even that close, i would just pull.

Now, I don't know if it was the downpipes that made my car rich but I am saying that we were both supposed to have the same tune and his car was much leaner than mine. What I can also tell you is that once my car ran the same a/f as his, my car was significantly faster. To me the catless downpipes were too loud, on my new car I am adding the catted downpipes.

I hope this helps a little bit but I know it didn't directly answer your question.

vdubpower

whats the DPs really gonna give you? even with a tune tuned for them, 20-30hp?

it all depends on what the goal is, what do u need a touch more hp for? if it everyday driving, you know its not gonna make a darn difference, u already have 600whp.

if u are getting it specifically for track and race purposes, then i guess it may make a difference...

xtyper

Yes, this would simply be to give me the edge at the roll-on Airstrip Events I like attending, where I've raced many cars that basically ran door to door with me.

xtyper

Thanks, this info was helpful. Out of curiosity, what tune were you and your friend running?

vdubpower

that reminds me i need to sign up for that november run....need new tires first , maybe pss's if i can get over that 295 fitment issue

Jshinone

I just want to have the advantage if I can. It was a good moment when I beat my friend who also has the same tune that I have plus my car sounds soooo much better than his does.

We both had a Renntech tune and then after that I had someone else take some fuel out of the tune after the downpipes. When it was tune to tune we were both very close, he would usually edge me out but it was very close. After the DP's and new tune it was not even close. The only thing that I regret is not dynoing the car and checking the air/fuels with the tune only.

xtyper

Interesting. Not sure that's really apples to apples anymore when you had someone else take fuel out. Who adjusted your tune? I'm guessing it wasn't Renntech, in which case it then would have likely become another vendor's tune entirely. And then it would be hard to tell if it was the downpipes or the new tune (or combo of both) that was responsible for the newfound power.

Jshinone

Yeah, I don't know exactly, I wish I had more information to give you on that. Like I said, the only regret I have is not checking the a/f's before the downpipes. I'm just trying to shed some light on everything. I would think that if you want to get the most out of your car you would want to have your car tuned for everything that you have done to it.

Traffic53

i have the Renntech downpipes on my wagon (200 cell cats) with the full Renntech tune. what the pipes will give you is amazing sound. they will also make the cars exhaust smell pretty bad. if you are looking for more power, there are better ways of getting 10-15hp than adding $5000 worth of pipes.

you get the pipes because they sound amazing. couldn't comment on the added benefit in sedan form

Faris63

I don't think the tune need to be adjusted for these downpipes from what I heard ! your tuner already turned off the cats sensors that what all tuners does with M157 tunes so even with catless downpipes you won't get CEL or ask Renntech about the CEL problem ? And the sound of catless downpipes is amazing

vdubpower

When u smog the car do u have to put cats back on

chawkins2001

Someone got bent over

Traffic53

so Renntech is f**king people now?

oh boy. it would be a privilege to all of us to hear you preach your knowledge on the subject.

carry on. teach us what you know.

AMG E Power

stop messing around and go catless DP's and regualr renntech tune !

emericr

Interesting question and posts. I will have shortly a separate post about this but I ran with another forum member at the Bradenton drag strip. We also did highway pulls and a dyno. (same 2013 CLS63).
He had the most aggressive Renntech tune and I had a "box" Eurocharged tune with catless downpipes.
I was off by less than a tenth on the quarter and trap speed was lower by about 3mph. He dynoed 604 on 19' optional OEM and I dynoed 541 on 20 inch. I would suspect the 20 inch wheels made a difference in the numbers because I don't understand how I would be so close to him if I were 60whp down. Eurocharged suspects that he needs to adjust the AFR but the dyno did not have that data or the ability to get the torque.
Eurocharged is planning a dyno and tune day in Miami and we will do dyno pulls for stock, tune and tune with pipes to show the difference. I will be able to report hard numbers then but for now, I would say I do not see any real improvement in power.
I did buy the downpipes for the aural feedback it gives. It is not for the faint of heart but is not as loud as the ones for the M-156 N/A 63 cars. They really work well and there is not much increased sound below 2.5Krpm but past 4K, it wakes up the neighborhood
Eurocharged has the cheapest downpipes (about 1.7K for catless and $2.5K for catted)

Faris63

Naahh just take it with tune and catless downpipes

vdubpower

and fail

drop997stop

I have mbh dp x pipe and 300 cell high flow cats and eurocharges new tune.

I started catless and then added the cats due to smells. Sound is amazing without the cats, especially downshifts. Smell was terrible so added the cats. The car felt signifcantly faster with the catless DP and tune compared to tune alone. Probably just the catless that created the most power.

sound changed when i added the cats, sounds almost stock now unless I get on it.

The DP are overpriced and the should be coming down in price. I think the tuners thought they could charge whatever they wanted and get away with it. I guess not.

My buddy got downpipes on his 2013 EVO and it cost 300 bucks,

drop997stop

I have mbh dp x pipe and 300 cell high flow cats and eurocharges new tune.

I started catless and then added the cats due to smells. Sound is amazing without the cats, especially downshifts. Smell was terrible so added the cats. The car felt signifcantly faster with the catless DP and tune compared to tune alone. Probably just the catless that created the most power.

sound changed when i added the cats, sounds almost stock now unless I get on it.

The DP are overpriced and the should be coming down in price. I think the tuners thought they could charge whatever they wanted and get away with it. I guess not.

My buddy got downpipes on his 2013 EVO and it cost 300 bucks,

Vic55

who keeps their cars long enough to smog them anyways?

MBH motorsports

We got downpipes for under $1600. 3 inch, 16 gauge, 304 stainless steel tubing, a massive 3/4 inch stainless steel flange that will not bend like 3/8ths will, 100% TIG welded, and Made in the USA... and they come with a lifetime warranty

The whole point of down pipes is the removal of the restrictions in the factory system. I understand, people like cats, and or need to run them... This is the only reason why we offer them.
If you are looking to gain anything from adding down pipes to your twin turbo 63, they will have to be catless to see any real gains. Otherwise, adding cats to a down pipe set up defeats the purpose in most cases. Sure you get a very small benefit of going from 2.75 OEM tubing to 3" OEM tubing, but thats really it.
Your, best bet is... If you have to add cats, add them in so they are removable and can be replaced with test pipes for track use. We have options for this.

xtyper

Mike, are the O2 sensor locations on your pipes the same as factory? I've heard if they are moved too much from the factory locations, it causes issues with the fueling and AFRs.

MBH motorsports

Unlike headers were you have no choice but to move the o2 sensors, our DP's have no reason to move then from there OEM locations really. Plus you only have so much o2 cable to work with, before need to run extensions or something like that.