So it sounds to me like you are keeping the factory exhaust, you just want to modify it a bit.

The factory Dp's are very restrictive with an 02 sensor and a precat directly behind the turbo's. The precat causes excessive heat. The other 02 sensor is located just before the main cat (if memory serves correct). If you removed your factory resonators and mufflers, you probably will not see any gains due to the Dp's. It will sound a little bit better though. You should not throw a CEL either since you are not messing with DP's which is where the O2 sensors are located.

Exhaust systems will certainly not yield massive HP gains. However, making it as free-flowing as possible will help your turbos. For example, putting on Vast Piggies or APR DP's will help your turbos spool better for much better air flow into your throttle body which will increase performance and it will reduce excessive heat which is a turbo killer and increase turbo longevity. Eliminating the central resonators will increase exhaust flow as will putting on high flow mufflers. It will also give the car better drivability and throttle response.

Take into consideration what you want to accomplish with your car....what are your long term goals.....and then create a list to making it happen.

OOOO

 

I always here about cutting resonators. What are they and what do they do exactly?

 

I belive they have nothing to do with emissions, but are only there to well, resonate the sound. Basically make the car quieter thats why cutting them out makes it louder. Anyway I'm getting my emissions tested and what not for two years on friday then cutting up the exhaut. I plan on gutting the pre-cats and putting 2.5" piping straight back to magnaflows with some nice tips. (ovals maybe...)

Now my question is what type of muffler should I go with? I hear some brands are restrictive? Any advice on a muffler that will be free flowing and not sound ricy. I really don't want my car to be annoyingly loud, but when I gun it I want to be heard!

 

Resonators don't create much if any back pressure, they are there simply to keep the exhaust quiet.

Removing cats won't give any significant hp gains without bolting on new IM, high flow catback exhaust, and after that, tuning.

You don't get gains from leggoing an exhaust system, you are just wasting money and effort, yes a full exhaust system from IM on does require tuning for any real gains... dyno proven.

People who take off thier cats to get 1 or 2 extra horse power (at most) are ********, we all live on the same planet, cats help prevent pollution and should not be removed for retardly minimal gains on a daily friggin driver.

 

Get magnaflow magnapacks!!!!! Its preaty much guted out mufler with some sound detaning around it. I never heard it on 2.7t but every other car that i heard with it has way deeper sound with some rumble to it. I just hope it wont be to loud.

 

My Friend, what I am about to say, I say with to you with the upmost respect. The people on this forum will bend over backwards to help you and anyone else who has questions about their car, so I would not blindly call people "********", especially the ones on this forum who are here to help.

Like I said, I mean no disrespect so if I am misunderstanding you, please feel free to enlighten me.

OOOO

 

I think my A6 is missing the resonators. It has the catalytic convertors towards the front and the mufflers at the rear, nothing in between. Since I bought it used, I don't know what was originally there. But last time it was in for an oil change I inspected the bottom with the mechanic and he commented I was missing resonators.

Since I never had them, I can't tell you what difference removing them made. The car sounds fine - not very loud but a decent growl under hard acceleration.

 

I'm only referring to the act of removing Cats to gain 1 or and unlikely 2 added hp, Cats help reduce emmision toxicity and there in, help prevent added damage to the environment, so if people are removing them on daily drivers just to get a super tiny gain... well it's just wrong, I'm not a tree hunging go green kinda guy but a little here and there helps to prevent or add to our planets longevity.

Test pipes do not give significant gains in comparison to "high flow" Cats, it has been tested in various venues, look it up, maybe 1 hp increase, just get a high flow Cat, we will all benefit from it.

 

I certainly know that exhaust systems do not yeild massive HP gains, I mentioned that in an earlier post. The reason I have my setup is to extend the life of my turbo's and it does give my car a much better throttle response. I am running test pipes currently and I have had my APR Hi-Flow cats on and there is not much difference if any. I am actually getting ready to put my cats back on since PA is areal PITA when it comes to inspections.

As far as our environment goes, I try to respect as much as possible and I knowthat my car running test pipes is putting more pollutants in the air but itsnothing compared to what our current government and major corporations are doing. Do you remember the Exxon Valdez!!

Peace!

OOOO

 

yeah well I'm just saying for people who don't know, GO TEAM, GO, GOoOOooOo GREEN!