//// Help me choose a downpipe ////

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
HI all,

Looking to get some PM work done to my car and I figure while stuff is being worked on / apart might as well upgrade a little too.

I know many people say the stock intake and exhaust are sufficient for a relatively stock situation like mine but I did have a relatively stock 1993 Dodge with the Cummins and a 4" straight pipe from turbo and it sounded sweet , had lower EGTs (not that I had EGT issues tho) and helped with fuel economy (granted some of that may have been the result of me babying it more after the exhaust upgrade since it was pretty loud and I didn't want to get grief from the man so I figured I'd do the same to the Jetta.

Anyways, I would like some input to help me make a choice ...

I am currently debating between ID parts 2.5 inch down pipe and Kerma's 3" downpipe.

1) I have a question regarding flow .... According to ID Parts, their 2.5 inch downpipe features a custom cast piece to gradually "flair up" to the 2.5" diameter downpipe pipe (I'm guessing this is similar to what my Dodge system had as far as a transitional "cone" to smooth / help prevent turbulence as the exhaust gas flows out of the turbo

I am not sure if Kerma's down pipe has the same feature ... i.e. a smooth transition from the turbo exhaust outlet to the 3" pipe..

Given the above, which downpipe flows better the 2.5" with smooth transition or the 3" non transition downpipe ?

2) Does the optional resonator make a real difference in drone reduction ?

Thanks in advance for all input / help

Andrew

FWIW - At the same time I'm upgrading the exhaust I am also going to install (or have installed) a BRM intake manifold with adapter (it's only been sitting in my shed for what seems like a year by now!) to help the intake side as well ...
 
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ghohouston

Veteran Member
Joined
Apr 2, 2013
Location
Lewisville, Texas
TDI
2001 Jetta Sedan TDI 5 Speed
If you're installing exhaust, just go with 3" turbo back. No where close to as loud as a 12 valve, but sounds great through the rpm range. Almost like a mini cummins
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
If you're installing exhaust, just go with 3" turbo back. No where close to as loud as a 12 valve, but sounds great through the rpm range. Almost like a mini cummins
HI

I see you have the same system on your car ... did you get the resonator option?

How is the drone or is there much of it ?... did you get any gains in mileage ?

I think it may be worth it just for the sound and possible weight savings tho...! (it's good if its not as loud as the cummims because that did pound on my head for long drives (of course the sheet metal interior with no floor mats or carpets probably didn't help!).

Thanks
 
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ghohouston

Veteran Member
Joined
Apr 2, 2013
Location
Lewisville, Texas
TDI
2001 Jetta Sedan TDI 5 Speed
Mine is straight piped. There really isn't any drone. Mine exits a little beyond the rear tire, at probably a 60 degree angle, I attribute this as the reason I don't have much drone. No mileage difference. Spool up is definitely improved with the larger exhaust/ straight pipe.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
unless your going nuts with your build, or you just simply want a full 3"
don't
go 2.5. much easier to work with and get things around. sound will be as nice.
 
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