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GTI downpipe on golf catback

jmsanders

Passed Driver's Ed
Location
ATL
I am picking up a cheap GTI downpipe to mate up to my is20 and wanted to make sure that the correct reducer is 2.5" to 2.25" to connect to the stock catback.
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
2.6 to 2.38

Highly unlikely you’d find an off the shelf solution for that.

The best you can do is a 2.5 to 2.38, so id recommend buying the reducer butt style, weld on. Once you have the reducer in hand have a fabrication shop cut the OAL of the reducer off then add it back on (weld). Then the downpipe will bolt right in.
 

jmsanders

Passed Driver's Ed
Location
ATL
HMM looks like there are a bunch of 2.5" to 2.25". I wonder if there is going to be enough room for me to try and finagle these two together
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
HMM looks like there are a bunch of 2.5" to 2.25". I wonder if there is going to be enough room for me to try and finagle these two together

Nope, 2.25 won’t work.

I was going to send you a link, but it turns out the supplier I use only makes 3” to 2.38 (which I use for 1.8T downpipe reducers and 2019+ Gti midpipe Reducers).

You’re next best bet would be to take the catback to an exhaust shop and ask the to expand the inlet to 2.6” OD so you can clamp it together.
 

Sc629

Go Kart Newbie
Location
IN
2.6 to 2.38

Highly unlikely you’d find an off the shelf solution for that.

The best you can do is a 2.5 to 2.38, so id recommend buying the reducer butt style, weld on. Once you have the reducer in hand have a fabrication shop cut the OAL of the reducer off then add it back on (weld). Then the downpipe will bolt right in.

if I wanted stock 1.8 dp to gti catback, would that be 2.25” to 2.5” or is it a weird size also??
 

nype

Drag Racing Champion
Location
Vancouver, B.C.
I was wondering about this...does the GTI DP actually fit the 1.8T?

If so, how do the midpipes differ (GTI vs 1.8T), diameter and resonator wise?

And does the GTI muffler direct fit the 1.8T midpipe?
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
if I wanted stock 1.8 dp to gti catback, would that be 2.25” to 2.5” or is it a weird size also??

There’s only two sizes.

Golf TBE = 2.38

GTI TBE = 2.6

Take either piece of either exhaust and that’ll be the size.

Nothing on any MQB golf, gti or R is 2.25. Period.

The charge pipes on all MQB cars are 2.38 aka 60mm, which some aftermarket brands don’t even realize (hence fitment issues).
 

TwinDad

Autocross Newbie
Location
Fort Lee, NJ
The 2.25 100% will work. You have to pick inner diameter or outer. You also have to trim either the downpipe or the catback to work. You need to make room for the adapter. On the gti downpipe side, you need 2.5" od. It will fit tightly inside the gti downpipe. I added about 4-1" relief cuts to help get it started. Then you tap it in evenly. A block of wood helps with this. On the stock catback side you need 2.25" inner diameter. The od will then be larger than 2.25". It will then be able to butt up to the stock catback and use the factory sleeve butt clamp. Think long term of your goals when deciding which one to trim for the adapter. I knew my catback was going to eventually go larger, so I trimmed off from that and not the downpipe
 

tigeo

Autocross Champion
Metric system for lyfe
 
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