GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

Does a Catted Downpipe really do anything??

Towerworld

Passed Driver's Ed
Location
Toronto
So I have a custom exhaust guy wanting to make a DP for me, he says he can use 3" pipe but the flange has to be 2.5" just like the stock DP. Seems to me like there will still be a substantial restriction with that flange, has anyone actually done a before and after Dyno run to show if Downpipes add any power? I have Unitronic Stage 1+ btw.
 
Last edited:

aloha_from_bradley

Autocross Champion
Location
AZ
You will need to tune for it, but yes, a less restrictive DP will add some HPs.

Turbo will spool faster as well. You'll see a more substantial gain over just a tune alone. I would encourage an intake / intercooler along with the DP if you're going that route, however. Most "stage 2" tunes account for those additional parts. Unless you get a custom tune with flash revisions or on a dyno.
 

new R Fan 2018

Passed Driver's Ed
Location
Oviedo, FL
Car(s)
MK7.5 R
I DEF noticed stronger pull and quicker turbo spool after adding DP/upgrading to Uni. Stg.2.(no IC)
 
Last edited:

NopeR

Autocross Champion
Car(s)
18 Golf R
It does nothing. That's why it's one of the first mods people do to highly increase power/torque via tune.

Don't get one. Waste of time.
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
On its own it won’t do much. But tuned, you can run a bit more boost and that’s nothing to write home about. The greatest thing about a dp is how much more boost the car will actually hold to redline

some people see the 20hp increase from stage 1 to 2 and don’t realize how much meatier the whole rev range is.

running a dp with a single high flow cat is beneficial considering you’re effectively removing 1 cat and making the one you keep high flow.

what will mess you up will be emissions. Stage 2 software tampers with emissions Readiness.

I’d also find a way to measure boost. Removing a cat could cause you to boost creep. This is more common with folks who delete both cats but even then. You never know.
 
  • Like
Reactions: krs

IanCH

Autocross Champion
Location
MA
Car(s)
'20 GTI
Unless he gets it tuned.

On its own? Not really.

with a tune? Yes.

Absolutely false lol. The downpipe is actually a mod that doesn't really need a tune to show its gains.

The downpipe does a LOT on this car, the stock one is extremely restrictive. The thing that most people don't realize is that they just look at peak gains and say it only adds a little bit. The downpipes main function in reducing restriction is to increase turbo spool and reduce how hard the turbo has to work to create boost and subsequently greatly increase the area under the curve of both tq and hp. No tuning is necessary to see the majority of these increases.

It is generally suggested to get a tune with a downpipe to turn off the CEL

The main reason aftermarket pipe designs are this beneficial is pipe design, diameter and smooth transitions in the curves. Aftermarket catless downpipes show next to 0 increase over catted versions, so don't cheap out and get one with a good cat.
 
Last edited:
Top