M3 GT4 x pipe?

[kyrix1st]

Curious if these came with 2 cats vs. 4 cats on OEM x pipe on our cars.
Any idea?

[k_mann]

Originally Posted by kyrix1st

Curious if these came with 2 cats vs. 4 cats on OEM x pipe on our cars.
Any idea?

I think akrapovic made the exhausts for the gt4 cars and they had no cats or resonators at all. Completely straight x pipe

[Lienrocs]

GT4 X pipe. No cats, no resonators.

[kyrix1st]

Originally Posted by Lienrocs

GT4 X pipe. No cats, no resonators.

Awesome. Could you share where you purchased the exhaust?

[Lienrocs]

Originally Posted by kyrix1st

Awesome. Could you share where you purchased the exhaust?

They don't make them anymore so you're gonna have to wait till a used one pops up. I picked mine up several years ago through a mutual friend. But if one comes up be ready to jump on it. They hardly ever come up and sell quickly.

[Redd]

An x-pipe is an x-pipe. Any straight thru x-pipe from any exhaust manufacturer would probably work the same.

That said, did anyone else notice the H-merge up front right behind the gearbox? And ahead of the main x-merge in the stock location?

[amrazM]

Originally Posted by Redd

An x-pipe is an x-pipe. Any straight thru x-pipe from any exhaust manufacturer would probably work the same.

That said, did anyone else notice the H-merge up front right behind the gearbox? And ahead of the main x-merge in the stock location?

difference really comes to weight savings and the H-pipe design equalizes exhaust pulsses

[Ben Ingraham]

Originally Posted by Redd

An x-pipe is an x-pipe. Any straight thru x-pipe from any exhaust manufacturer would probably work the same.

That said, did anyone else notice the H-merge up front right behind the gearbox? And ahead of the main x-merge in the stock location?

X-pipe is not any other X-pipe. For difference in delivery in power can be done through bends and diameter. In regards to Akra, GT4 pipes don't sound the same and are manufactured specific to the V8. Titanium also doesn't sound the same as stainless.

[Redd]

@kyrix1st are you running a tune? Might need a custom tune since this GT4 X-pipe has a forward merge.

[Lienrocs]

Originally Posted by Redd

@kyrix1st are you running a tune? Might need a custom tune since this GT4 X-pipe has a forward merge.

The GT4 merge is in the same location as stock, I think. I never put the two next to each other but the merge is right at the support bracket.

[Redd]

Originally Posted by Lienrocs

The GT4 merge is in the same location as stock, I think. I never put the two next to each other but the merge is right at the support bracket.

If you look closely, there is a H-merge very far forward, right behind the gearbox.

[Lienrocs]

Originally Posted by Redd

If you look closely, there is a H-merge very far forward, right behind the gearbox.

Let me get my microscope out so I can look a bit more closely.

I realize there is an H merge farther up but I'm not sure that is going to have the same scavenging affect an x merge has. If you look closely the x merge is in the same location as stock.

I've been running my GT4 X for 2 years and almost 20k miles with a catless tune. I think the tunes you're thinking of are for mid sections with the actual x as far up as they can go.

The GT4 does not require anything special from a regular catless tune apart from disabling the rear O2 sensor because there is only one O2 port per side rather than two.

[SAMM3Y]

You can still buy the the H merge link pipes (section 1) directly from akrapovic for about $1k, you could then have a muffler shop/ti fab shop build you an x pipe to match whatever rear section you wanted if you desire a gt4 setup.

[Redd]

Originally Posted by Lienrocs

I've been running my GT4 X for 2 years and almost 20k miles with a catless tune. I think the tunes you're thinking of are for mid sections with the actual x as far up as they can go.

The GT4 does not require anything special from a regular catless tune apart from disabling the rear O2 sensor because there is only one O2 port per side rather than two.

Hmm... I already have a full decat exhaust with the x-merge in the stock location (under the center bridge bracket). I thought of getting a local exhaust shop to add a H-merge in the forward GT4 location. I'm running a BPM Stage 2 tune, so I reached out to BPM who told me that a forward merge might affect low rpm driveability. But I think they were referring to a forward x-merge like in the BW X-pipe. Now you got me thinking if I should go ahead and try out this GT4 H-merge.

I wonder what gains adding the H-merge would have, if any?