jellofuel

My z doesn't have a before dyno, but I'm running the Tomei Expreme V2 headers with Motordyne ART pipes. It's an excellent combo, my cammed non-revup makes 300 whp and 284 wtq - but my only concern is the expremely (ha!) small mismatch between header OD and test pipe ID. I think the OD on the Tomei is 2.36", and ID on ART pipes are 2.25". I think non-stepped ART pipes might be ideal, eg 2.5" straight through, but the helmholtz resonators would most likely need to be resized.

thedoc092

hmmm...thats strange, to my knowledge the Nismo Headers have the 2.25" OD which would be a perfect mate to the ART pipes im gonna be running. Maybe that will change my decision a bit from the Tomei's which were the ones i was planning on getting. Any idea on what the Z1 headers diameter is at the merge collector?

jellofuel

The OD on the Z1/Momentum is 2.25" if I recall correctly. During my research, I found the primaries are completely different. I chose Tomei over Z1, as there's no doubt at all in my mind regarding the equal length primaries. The primaries differ between the two as well. (Can't remember sizing off the top of my head)

thedoc092

hey Jello, any idea what the diameters are on the Tomei Expreme non V2 headers are?

thedoc092

Id prefer Tomei's as from all the good things ive heard about them but just not sure with the V2's not having the same diameter at the OD as the ID of the ART's, im kind of **** with that kind of stuff lol.

jellofuel

I double checked the Tomei site. The Tomei headers are amazing, I know there are dyno's for them on the forum somewhere.

Primaries 42.7 mm = 1.6811"
Outlet 60 mm = 2.3622"

https://www.tomeiusa.com/_2003web-ca...i_ver2-en.html

thedoc092

Not to sound too noobish here, but i havent really dealt with headers before. How does it work properly with the outlet of the headers being bigger than the inlet of the ART pipes? That doesnt cause any pressure issues or anything?

jellofuel

There aren't any issues with this setup. I have the Tomei headers, and ART pipes - if anything, there might possibly be a venturi effect, however, I'd be unable to prove that. They do sound great paired together though.

DarkZ03

iTrader: (11)

Ok, since I have done quite a bit of research of the matter and went to school for stuff like this.... It does matter, but any issues are a "could happen" type of scenario. Having a step at the outlet (mating pipe is smaller) could cause exhaust pulse reversion which is bad, having it mated to a bigger pipe could slow exhaust and scavenging. Tomei are indeed 60mm the Z1cats match perfectly, I can understand you being **** about that, I feel for same way because my exhaust is smaller than everything else....fortunately the exhaust I want to get is 60mm so it would all match. One thing to keep in mind is Tomei tested several collector diameters and picked the best one, which I don't think anyone else making shorty headers has.

thedoc092

hmm...the more i think about this the more frustrated i get!! I really like the Tomei's alot, but the dilemma is very present. Which test pipes or hfc's are u looking to run DarkZ that mate up to the 60mm collector on the Tomei's? i checked the Z1 HFC's and only info i found on them was that were only 2.5", unless they have some that i didnt see that are indeed 60mm.

DarkZ03

iTrader: (11)

60mm tubing is really close to 2.25" honestly they looked the same when I installed them (and I'm pretty good with measurements) I think Tomei test pipes are the same size as the headers and AAM. Z1 cats tend to be popular with the 370 crowd because they don't have rasp and they are pretty tiny lol. I think the substrate is less than 3" long =)

thedoc092

yeah it is pretty close in measurement but for me and my experience with things like that, if something could potentially go wrong...it usually does for me lol. id love to run the Tomei's along with the ART's and Shockwave...but i'm gonna have to fight the demon of that potential problem u touched on earlier. Worse case if i decide to not risk it ill prolly go with the Z1 headers along with the ART's and SW. atleast then my mind will be clear on the mating measurements. The Tomei's are awesome though no doubt, gonna be hard to sway away from them i think...but who knows.

jellofuel

I don't think anything would go wrong with the slight mismatch, since they're so close together. I was running ART pipes with HKS true dual exhaust for a while - the ART pipes have OD of 2.5", and the HKS has 55mm piping, or 2.165".

I'm running Tomei headers with ART pipes with no issues.

DarkZ03

iTrader: (11)

You may actually be good because of the hemholtz resonators on there. I'd suggest the following, if you want to got with Tomei contact motordyne and ask them about it, though I wouldn't want any bottlenecks in the exhaust. Are you going with ART for the sound or gains?

thedoc092

I love the sound of the Shockwave which is why i decided on that for the exhaust, as for the ART's, i definitely wanted to swap out the stock cats there so i figured mate them with mid's from the same company to assure compatibility. The sound is great on them but im not married to them, i wouldnt be opposed to getting different ones.

DarkZ03

iTrader: (11)

Ok cool, they might even make the ART in different sizes, you may want to ask them.

DarkZ03

iTrader: (11)

Hello isn't the HKS 60mm? At least the twin muffler is.

thedoc092

i know the gains on the ART's and SW are well documented...and proven. Which i definitely like, but again, wouldnt be opposed to different ones that would mate up properly if i decided to go with the Tomei's as opposed to the Z1's.

In the end i want to be as seamless as possible and everything mating up perfectly...again, im **** about that kind of stuff lol

thedoc092

hmm...i honestly dont know. ill have to look into that, curious to find out.

jellofuel

The piping on my HKS was 55 mm, though the size can range. I did find the HKS TD on conceptz's website with 60 mm piping. However, 60 mm = 2.36", which is less than the 2.5" OD on the ART pipes. I ran that setup for a year without issues, and it sounded great.

Personally, I swapped out the HKS for resonated XYZ and Z1 single exit for performance. My goal is max power, and least weight, and this combo fit the bill perfectly.