Downpipes & Best Practices

[Heavy Dupree]

Great diagram where did you get that? Whoever at Nissian designed this needs to be fired! So many different diameters of piping.

That diagram is directly from HKS-power.jp

https://www.hks-power.co.jp/en/product_db/exhaust/db/33711

 

[Neutr0n]

without opening a new thread on this topic, may i just highjack to ask:
What is the difference between these two brands other than the price?
https://spoolperformance.com/collec...ade-race-downpipes-infiniti-q50-q60-rz34-vr30

https://www.amsperformance.com/product/ams-performance-infiniti-q50-q60-race-full-downpipes/

any reviews would be appreciated

 

[T3R5Z]

without opening a new thread on this topic, may i just highjack to ask:
What is the difference between these two brands other than the price?
https://spoolperformance.com/collec...ade-race-downpipes-infiniti-q50-q60-rz34-vr30

https://www.amsperformance.com/product/ams-performance-infiniti-q50-q60-race-full-downpipes/

any reviews would be appreciated

To be honest if you are getting straight through pipes there would be not much benefit in getting the AMS ones. There is not much engineering you can do on a three inch straight through pipe.

 

[Heavy Dupree]

without opening a new thread on this topic, may i just highjack to ask:
What is the difference between these two brands other than the price?
https://spoolperformance.com/collec...ade-race-downpipes-infiniti-q50-q60-rz34-vr30

https://www.amsperformance.com/product/ams-performance-infiniti-q50-q60-race-full-downpipes/

any reviews would be appreciated

The only difference I see is that the O2 sensor extensions look longer in the Spools DPs compared to the AMS.

 

[ZMidlife]

There is only one sensor per side and its the lower. The Upper will still do its job and wont throw CELs

I went full for both, switch over to catted to prevent 1. bad smell and 2. Rasp. The hi flow cats will perform just as good as catless

The big difference will be the metallic vs ceramic materials in the cats.

 

[T3R5Z]

I installed the AMS catless LDP this weekend. The install was fairly easy but time consuming as I did it on jack stands.

I still retained the OEM cat in the UDP not CEL it any issues so far.

The LDP is probably the most restrictive part on the car. It goes from like 2.5 inch down to ~1.5 inch. I measured the UDP at about 2.75 inches going into my 3 inch exhaust.

Car sounds much better. You get abit of a deeper tone, more spoil noise and a VQ rasp.

 

[thesilverbullet]

I installed the AMS catless LDP this weekend. The install was fairly easy but time consuming as I did it on jack stands.

I still retained the OEM cat in the UDP not CEL it any issues so far.

The LDP is probably the most restrictive part on the car. It goes from like 2.5 inch down to ~1.5 inch. I measured the UDP at about 2.75 inches going into my 3 inch exhaust.

Car sounds much better. You get abit of a deeper tone, more spoil noise and a VQ rasp.

Thanks for the info. from the pictures, it looks like the upper exit necks down to ~2” OD with the ID being even less.

is the picture different than reality? I was looking at the full dps to get rid of the bottle neck in the upper, but if the upper’s exit is really 2.75” OD exit, I’m going with lowers only.

and merry christmas to everyone…

 

[T3R5Z]

Thanks for the info. from the pictures, it looks like the upper exit necks down to ~2” OD with the ID being even less.

is the picture different than reality? I was looking at the full dps to get rid of the bottle neck in the upper, but if the upper’s exit is really 2.75” OD exit, I’m going with lowers only.

and merry christmas to everyone…

Interesting now that I look at the diagram and do the conversation.

I'm in Australia so I'm not sure if it different in the US but the UDP flange was significantly bigger then the flange that connects the LDP. That's not shown in the diagram it just has one measurement.

*I ran it through AI and the upper cat appears to be about 4 Inches. At 600 cell it flows the same as a 3 inch straight pipe.

Based on that there would be no point in changing it unless you wanna. Make huge power and are changing turbos ect..

Definitely worth changing the LDP I'll remeasure it when I get home.

 

[thesilverbullet]

Interesting now that I look at the diagram and do the conversation.

I'm in Australia so I'm not sure if it different in the US but the UDP flange was significantly bigger then the flange that connects the LDP. That's not shown in the diagram it just has one measurement.

*I ran it through AI and the upper cat appears to be about 4 Inches. At 600 cell it flows the same as a 3 inch straight pipe.

Based on that there would be no point in changing it unless you wanna. Make huge power and are changing turbos ect..

Definitely worth changing the LDP I'll remeasure it when I get home.

Thanks for the info.

Can you confirm the weld joint (from upper cat to the upper’s exit flange) is the same (2.75”) as the flange exit point or is the weld joint smaller as it appears in the picture.

 

[Bumflik]

3.0 inch Spool Performance Race version no cats LDP

 

[Bumflik]

Thanks for the info. from the pictures, it looks like the upper exit necks down to ~2” OD with the ID being even less.

is the picture different than reality? I was looking at the full dps to get rid of the bottle neck in the upper, but if the upper’s exit is really 2.75” OD exit, I’m going with lowers only.

and merry christmas to everyone…

Merry Christmas to you as well!!!!!

 

[FatRatZ]

FYI - I replaced LDP with ISR and installed a Stillen piggyback tuner. AWE Touring exhaust.
It throws a code / CEL. Seems to code mostly in more aggressive maps.
I cleared the codes but these may be permanent write codes - that is, the light is off but a dealer can still see the code when connecting through consult.
I read some people space the second O2 sensor to mount further out/ protrude less into the pipe - is that a thing that works?

 

[thesilverbullet]

it should help but no guarantee, it’s an old fashion lawnmower spark plug defouler or o2 sensor extender. This is why ams has the extended o2 bung welded into the pipe for you.

You can also pack the extender with steel wool. The best solution is to have a tuner to disable the o2 check in the ecu.

 

[thesilverbullet]

for Honda’s you can do your own tuning using hondata - including disabling the o2 check. When disabled it also reports the cats are present and good for emission checks.

I’m sure an ecutek tuner can do the same for the z - but they are not going to post this info on a public forum. Keep in mind this is for off-road applications only - lol

 

[T3R5Z]

FYI - I replaced LDP with ISR and installed a Stillen piggyback tuner. AWE Touring exhaust.
It throws a code / CEL. Seems to code mostly in more aggressive maps.
I cleared the codes but these may be permanent write codes - that is, the light is off but a dealer can still see the code when connecting through consult.
I read some people space the second O2 sensor to mount further out/ protrude less into the pipe - is that a thing that works?

Strange I contacted AMS before I installed mine as I'm not ready to tune my car yet. They advised me that I wouldn't get a CEL and it's been good so far.
The science is sound as the sensor is after the factory cat.