Section 2 - 3" Y-pipe tq loss or gain?

[CyclingTurtleM3]

Recently got a tune from HTE performance and I'm looking to upgrade my section 2.




Currently I have SG headers and OEM section 1, 2, 3.




HTE mentioned with my current setup and tune the car makes about 330whp. Which seems high, but let's say it's at 330WHP. Will a single 3" pipe in section 2, like rogue engineers xpipe or status gruppes xpipe, be able to handle the flow?

Would a 3.25 be better or stick with dual 2.5"?

I've read different forums that state the single 3" Ypipe in section 2 will kill your low end tq, but some say it won't.




Any thoughts or tips?

[Tbonem3]

Y pipe loses midrange, barely gains much up top.

True 3.5" will at least give you more on the top, which is for a track car.

For all around performance and or street, go with dual pipe. 60mm is fine, but as you do more mods like cams, especially, there are good gains with 2.5" dual pipe.

[maw1124]

Where does an H pipe factor in here, if at all? Is it an upgrade over stock? Or is stock optimized for these levels of gains?

maw

[Tbonem3]

Stock is an H pipe, right after the sect 1 to 2 joint.

Older company, CPI, used to put an H at the end of their sect 1. I'm not sure that helped, having 2 but you DEF want 1 H in there for torque. And with the oversized SS dual pipe sect 2, there's no longer much reason to go to 3.5" single. 2.5" dual can support lots of power.

[maw1124]

That’s what I thought. Translation: changing your Section 2 isn’t really an upgrade unless you’re going forced induction. That’s always been my shorthand anyway.

maw

[Tbonem3]

I wouldn't quite say that though. Even without cams, I felt the car was stronger when I tested one. Cams and Injectors, with airbox/headers/tune ofc, I would say should be accompanied by 2.5" piping (all the way via SS stepped or at least from the sect 2 onwards (ss can do 2.5" sect 3, but there's scza, dinan, Megan, and a few other out there as well).

I prefer the sound of stock piping, however, and since I have no cams or anything beyond airbox/headers, I don't bother with larger piped sect2 or 3.

[Sharocks]

First, 330whp is high for just those mods.

Most S54's make like 300whp if that* with just headers.

A Y pipe changes the sound and makes the tone deeper and tad louder.

A dual 2.5" will net the most power but only if you require it aka airbox, cams, etc.

If you don't have any of that, I would do those things first and then retune to see where the restriction is.

[OldRanger]

Is the concern about a Section 2 Y-Pipe to a 3.5 (Like Bimmerworld) that the engine will produce less torque? So for example, if I have a 93 octane tune from a reputable tuner, and I have a completely stock exhaust...will I see reduced torque if I throw on a BW 3.5 exhaust for Section 2 and 3? I'm not a math guy, but is it substantial enough to offset the power-to-weight improvement?

Observation: a very high percentage of track and race cars use a single pipe exhaust. Even on tight tracks where torque is critical. (I acknowledge most track cars have headers and a tune)

[rGTIedge]

FWIW, I put on a custom 3.5" Y pipe setup, and felt a noticeable loss in mid range torque, as described. I do feel like the car pulls harder up top though, which is ok for me, as it's mostly a track car. It is LOUD and throaty, even with the added resonator. Exhaust pictured (sorry if the pics are gigantic)

[AWE46M3]

I went with the super sprint twin tube resonated section 2 after reviewing this write up by Obioban.

In retrospect, the section section 2 was probably good enough. I am very happy with it and plan to run it for the foreseeable future .

https://nam3forum.com/forums/forum/m...-2-5-section-2

[Actuary]

Does anyone know if a tune is needed if you're changing section1 or section 2? I have SS stepped headers with euro cats in section 1, paired with the old SS y-pipe and looking to hopefully upgrade to HJS in section 1 and the twin pipe in section 2.