Built a Custom downpipe and exhaust system for i4

Gcc91 · Oct 14, 2024

Hi,
New here just finished fabricating a custom exhaust as weren't many options for a bit of fun.
Going to put on dyno this week and attempt a tune. Anyone had any luck?

cyanmauve · Oct 14, 2024

Cool! No muffler? How loud is it?

patrickramdial · Oct 14, 2024

Bro, that looks so clean. And sounds great also!

Andy H · Oct 14, 2024

Nice work. Does that bypass the valves too? Are you getting any drone at highway speeds?

kitkat · Oct 14, 2024

Andy H said:
Nice work. Does that bypass the valves too? Are you getting any drone at highway speeds?

There doesn't seem to be a muffler to bypass

Nova · Oct 14, 2024

I see a flame at 8 seconds into the video.

Dragoon · Oct 14, 2024

It looks like you also have some nice weight savings! Sounds great!

seriously · Oct 14, 2024

surprised how good it sounds. I would have guessed it to be over the top loud.

Gcc91 · Oct 14, 2024

cyanmauve said:
Cool! No muffler? How loud is it?

It's loud haha

Gcc91 · Oct 14, 2024

Andy H said:
Nice work. Does that bypass the valves too? Are you getting any drone at highway speeds?

I haven't had a decent drive yet thought it might throw itself into limp mode with the o2 sensors and egt in downpipe not having any difference in pressure. Will be putting computer on it this week and will have some more updates

crashprash · Oct 14, 2024

Wonder what a design like this would sound like on a v6

Gcc91 · Oct 14, 2024

crashprash said:
Wonder what a design like this would sound like on a v6

Would sound amazing I think. Yet it may require more back pressure been supercharged. Turbo spins better without back pressure. Little different

lynchy73 · Oct 15, 2024

Gcc91 said:
Hi,
New here just finished fabricating a custom exhaust as weren't many options for a bit of fun.
Going to put on dyno this week and attempt a tune. Anyone had any luck?
View attachment 53341

How are you gonna tune it? I didn’t think there were many options on tuning the AMG ECU?

Porter · Oct 15, 2024

seriously said:
surprised how good it sounds. I would have guessed it to be over the top loud.

Rotary mufflers are quite effective at lowering the total volume level of a modern engine. Surprisingly so in some applications, this one included.

Gcc91 · Oct 15, 2024

lynchy73 said:
How are you gonna tune it? I didn’t think there were many options on tuning the AMG ECU?

The tunning company lm using is remotely accessing while I'm on dyno tomorrow. Will keep you updated if we have any luck.

lynchy73 · Oct 15, 2024

Gcc91 said:
The tunning company lm using is remotely accessing while I'm on dyno tomorrow. Will keep you updated if we have any luck.

Great. I did find some info regards tuning these AMG motors. I believe you need to fit a “virgin ECM” to tune them beyond a certain point.

Wusah · Nov 13, 2024

That sounds great!

RaynesCars · Mar 31, 2025

Gcc91 said:
The tunning company lm using is remotely accessing while I'm on dyno tomorrow. Will keep you updated if we have any luck.

Assuming they hit a stumbling black?

Built a Custom downpipe and exhaust system for i4

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