B8 A4 Downpipe VS Midpipe

[NotChristopher]

Hey everyone, can someone please explain the differences between a midpipe and a downpipe? I'm currently running straightpipes from the cat back and want to make it louder and eventually slap a tune on it. Which one would make it louder and be better for a possible stage 2 or 3 tune in the future?

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[pekarjm]

Hey bro... so a mid-pipe would be a resonator (a sound detoner) and a down-pipe (pipe directly after turbo/exhaust manifold) is refered to as a catalytic converter. The "cat" or down-pipe sounds the best when replaced with a hfc (high flow cat). It gives it a nice crackle sound we all love. IMO, the mid-pipe doesn't sound that good comparatively speaking... but way cheaper route if u can weld.

Keep in mind, u need a tune for a hfc. Where I live in ohio, we have bullshit emissions laws and require a e-check. I have an apr stage 1 tune. I am getting a stage 2 next week which requires a hfc. I know for a fact replacing the mid-pipe has no effect on hp/tq gains. If u live in a area where u need e-checks to renew tags/registration u have to use a hfc and NOT A TEST PIPE. THIS WILL SET OFF CHECK ENGINE/MIL.

If u don't get a tune with a hfc, u will actually loose power cause u don't have enough back pressure to spool the turbo. And of course set off the MIL/check engine light. I'll keep u posted on if I need a spacer for the rear O2 sensor bro!


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[NotChristopher]

Awesome, thanks for that good information! Ill definitely be checking out some downpipes now. Sorry about emissions 😭 Goodluck getting that tune and let me know what gains you get!

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[planekiller1]

Been looking for a long while at getting a test test pipe but wondering if its worth the change without doing the midpipe as well at the same time. Obvously will be going stage 2 so tuning anything extra in isnt an issue if I do it before.
-Kurt

[wkhanna]

I bought the mag exhaust from this guy.....

...the unitronic kit he has is still for sale & is a really good deal, imho......

LINK