One of my friends has C63 stock and he has LT, downpipe, CF intake, and K&N filters not installed yet. He would like to install them ASAP but wants to drive the car without tune for a while. Will his power decrease or increase or stay the same?

His car is 2009.

It will most likely lead to some A/F ratio issues, I would not recomend it

has nothing to do with power increases or decreases, he will most likely get CEL's and could damage his engine if it runs lean.

Of course AFR is important n forgot to ask about it . So better to wait then install all + tune !!!!

Thanx for the info

With the installation of these hardware parts, the engine will be moving a lot more air. But, the stock fuel maps will only inject a set amount of fuel. So, you have more air, but insufficient fuel. This can lead to a lean state which would not be advisable if you want to push the engine to higher rpms.

If you're running LTH's with a downpipe, there is almost certainly something wrong!

The answer to your question is "probably not". The question for you is what is your risk tolerance?

He asked 3 questions: Increase? Decrease? or Stay the same?

Which one were you responding "probably not" to?

Just curious.

uggg. my reading comprehension skills are poor.
Somehow I read it, and assumed he was talking about reliability.

Power will increase. Increased flow=increased power. Only issue is if you set off a sensor and the car goes into safe mode.

I wouldn't be too hard on your reading comprehension skills. The question was compound so, kind of hard to answer that kind of question without breaking it up.

I appreciate the feedback.

so, the ecu will adjust to the increased movement of air but there are built in limitations that dont allow the ecu to adjust fully to the fuel needs of a freer flowing exhaust?

am i understanding this correctly?

Yes, the built-in limitation is just stock programming that is meant to match stock hardware.

Historically, catback exhausts have not been shown to create AFR issues. But, LT's, which remove cats are a completely different story. They exhaust much more air than stock manifolds and because of this, the engine can pump much more air than stock.

LTH's without a tune is not recommended. His engine is going to run lean and throw off the air fuel ratio.

Like another poster said, the ECU can adjust the AF, but only to a certain degree. It wont compensate for headers.


To the OP: Google, "Detention"

Too much air not enough fuel. Need to tune. Or ping ping ping.

Detonation not Detention = Punishment you got for acting out in school!

Thanx everybody for your feedback n comment. We decided to wait until the tune time.

Smart move

Whoopsie. Maybe its cause I am on a detention right now that I was subconsciously thinking that..

K&N Filters alone will be fine however. I am proof...

+1