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Cast Downpipe vs Mandrel bent tubing+ resonator...which one is more quiet?

kc10131984

New member
Location
Santa Valley, CA 92708
Car(s)
2017 GTI Autobahn
I'm in the market for a GESI/Euro 6/HJS downpipe that is also low on the noise.

I know that cast dps are quiet due to the heft of the connection to the turbo, but unfortunately it appears that no one makes a cast downpipe that also has a resonator and a high end cat on it. I know APR did this, but it's now discontinued and I'm also not a big fan of their o2 sensor location and requiring a tune to wipe CEL errors.

Alternatively, I'm seeing normal non-cast mandrel bent DPs feature both high quality cats and resonators (e.g. MAP performance). Does anyone know if I can expect the same amount of noise from a cast DP vs a non-cast DP+ resonator?

I'm just trying to decide between MAP performance (non-cast+resonator) vs say Miltek/Cobb (Cast but no resonator). Any insights or opinions would be appreciated. Thanks!
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
A sufficiently sized resonator won’t fit in the downpipe, it belongs in the Midpipe aka the first section of the catback.


The difference between cast and tubing is negligible, especially since all of the cast options are only cast for a few inches.
 

kc10131984

New member
Location
Santa Valley, CA 92708
Car(s)
2017 GTI Autobahn
Hi Jake, thanks for your help. That all makes a lot of sense to me.

When you mention that a sufficiently sized resonator won't fit in the downpipe, is it safe for me to infer that those resonators that are commercially sold as part of the downpipe (e.g., the map performance one) are thus insufficient in size, and therefor the difference to sound/drone reduction they make are marginal/negligible, compared to the same downpipe but without a resonator? Or is it still worth the additional cost, if low key is my ultimate goal (with the understanding that most of my noise reduction will still ultimately be coming from a resonated midpipe on a catback)? Thanks again.
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
Hi Jake, thanks for your help. That all makes a lot of sense to me.

When you mention that a sufficiently sized resonator won't fit in the downpipe, is it safe for me to infer that those resonators that are commercially sold as part of the downpipe (e.g., the map performance one) are thus insufficient in size, and therefor the difference to sound/drone reduction they make are marginal/negligible, compared to the same downpipe but without a resonator? Or is it still worth the additional cost, if low key is my ultimate goal (with the understanding that most of my noise reduction will still ultimately be coming from a resonated midpipe on a catback)? Thanks again.

Correct, any resonator that’ll fit in the downpipe is basically a waste of money on this platform as it’s not large enough to be effective.




The Vibrant 17950 just plain works for these cars, and it’s too large to fit in a downpipe.
 
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