V6 X-pipe VS H-pipe flow test
 

I am looking into a replacement exhaust for the Borla Type-S which came on the car when I bought it. I ran across this while searching V6 exhaust on other platforms as I felt what is good for the gander. Apparently the H-pipe flows better for top end power, while the X-pipe flows better for low end power.

I have only seen 2 exhaust which use an X-pipe while searching. The Invidia Gemini and the Greddy Evolution G. It's seems most use an H-pipe. I think the Borla Type-S does and the factory oem Nismo exhaust does which he took off the car. Not really sure why he even changed it as the car doesn't seem louder than stock. Luckily he gave it to the dealership if I want to swap it back on. I'm almost tempted to just put the oem one back on and just change add headers and high flow cats.

Does anyone know if there is a significant gain of hp/tq for a modified car using 2.25" piping vs 2.5" piping?

If you have any suggestions on exhaust let me know and please include a dyno showing the gains. Here is a link to the video.

https://www.youtube.com/watch?v=2crCWF5cmLk

The Ark exhausts have 2.5 diameter piping and probably the nicest X-pipe in the industry. It’s what convinced me to go with the Ark DT-S. By the way, the Nismo OEM system has an X-pipe not a H.

OEM Nismo flow path.
 

According to this thread it's an H-pipe as found on the R-Tune exhaust.

https://my350z.com/forum/2009-370z/4...formation.html

Yeah all 3 of these look great but I think I am leaning towards the Greddy since the piping looks like it would flow a lot better. Then again I heard the Greddy is mad loud and I want something liveable so maybe Invidia.

https://ibb.co/tHqhBTL
https://ibb.co/KxNK6JC
https://ibb.co/dBRPn6X

I stand corrected. Just went and check my Nismo OEM exhaust in storage and it is an H-pipe.

I might just keep the Borla on for the first fbo and bolt ons. I mean it's what's on the car so might as well give it a shot.

Check into Fast Intentions. You want dyno numbers, they are on their webpage or here.

For any one interested, here is a pic of the X-pipe on the Ark DT-S system. Took it before installation. Quite impressive.
Attachment 144897

Per Ark website, this system is good for 10 whp and 9 wtq.

You are correct. It is an H-pipe. I had the R-Tune installed. I drove a new Nismo before I bought the R-Tune. I may be half deaf, but I couldn't hear much, if any, difference sound in sound between my car and the Nismo. There is a huge difference in sound between the stock Nismo exhaust and the R-Tune.

It is a little louder than stock, but it is MUCH more melodious. I can't tell any difference in power, but I mash on the pedal more just to listen to the music.

Nismo R-Tune
 

I decided to go with the Nismo R-Tune Exhaust because it is 2.5" and the fact it's Nismo. I felt that it's only right to put a Nismo exhaust on a Nismo. The exhaust also uses an H-pipe. I really wish I could do back to back dyno with an X-pipe vs H-pipe to see which makes the most power on the cars. But I think the power is negligible. I think it all comes to sound.

Please post feedback after you get it installed! Does it take away from any of the high-pitched VQ whine?

Borla to Nismo
 

The exhaust on the car currently is a Borla S-type which was installed by the previous owner. All I can let you know is what it sounds like now and what it will sound like. I'll do a before and after video of the sound.

The only thing I don’t like about the R-tune exhaust is the single layer exhaust tips. The OEM Nismo tips are resonated double-layered. But since they’re removable, they can always be changed. Enjoy and post up some sound clips once installed.

Yes, I see the Nismo S-tune and Nismo titanium exhaust are double layer. I wonder if you can order the tips from an S-Tune and mount them.

Both are very close to each other. For these cars, it seems like Y-pipe style exhausts make the best top end.

I compared a dual 2.5" exhaust w/ an X pipe to a motordyne style exhaust with a 3 inch mid section back to dual 3inch and it picked up about 6-10 whp.

In theory, the dual 2.5 inch flows more but the Y style made more power.

Here....

Interesting video, thanks for sharing. Interesting note about the Y piped exhausts at the end there. It seems like Y pipes and a single exit seem to be beneficial on our cars as well- at least from my reading.

It does appear that an X-pipe does offer better high speed flow and better low speed scavenging effect over an H-pipe. Furthermore, it appears that a more open-type X pipe improves on those qualities. Interesting! I’m just wondering when is too much. In my case, I have noticed a definite improvement in engine smoothness at high revs with my Ark DTS catback.

GReddy Evolution GT for the win!
 

I have the GReddy Evolution GT catback exhaust with Fast Intentions high flow cats and it is loud but once it's warmed up it's not too bad. It's definitely a cleaner and overall better sound than if I had test pipes. Also, that catback keeps the OEM exhaust tone while enhancing it.

It flows pretty good mid-range to redline. I found that I lost a little bit power, mostly torque, below 3500 rpm.

The sound is very nice and my friend who has a Magnaflow on his G37 likes it a lot ;) I read somewhere that the Nismo OEM exhaust was made by GReddy but don't quote me on that.

Actually the OEM Nismo exhaust was made by HKS. Having removed it I can tell you that it nothing special and was made to a certain price point. This means that it has approx. 2 inch diameter piping, MIG welded (not TIG) and the H-pipe section appears even smaller. It has "dirty welds" (not smooth) on the inside of it. I doubt that there is much scavenging effect. Furthermore, the back muffler section does have better flow than the standard muffler but it is extremely quiet. My grandmother's Camry is probably louder. I personally think Nissan completely and royally dropped the ball on the Nismo exhaust and relied more on the fake exhaust sound inside the cabin to make up for no exhaust sound outside the car. But, luckily it is easily fixable with the numerous aftermarket exhausts available for our cars. :driving: