I was thinking what was it about this new Y that would make any difference when other Y pipes apparently don't do anything? It might be because the merge looks better or more (IMHO) because the Y merge is noticably further back than before. There was one other aftermarket Y that had the merge collector further back. It was a really simple unit. Just basicly two straight pipes that merged as late as possible to avoid any bends. Motodyne's Y doesn't look to be pariticularly further back but it just could be the picture. He did briefly mention the merge placement and said that was ideal accoridng to his research

 

I definitely see more gradual bends and it looks like the HR Y might potentially be a little less restrictive to boot. Good find.

 

I'm not feeling those bends right after the cats.

 

There's a whole bunch of them here:
http://www.350z-tech.com/zwiki/Part:Y_Pipes

Pic of what I referring to:

Oddly enough, this Tanabe might be decent. As the Y merge is far back and the merge isn't too large (IMHO 3" collector and catback might be too big for good flow)

Here's a stock Y w/o the shields for reference: Pipe looks pinched down at each flex. And it's looks to be a crush bend on each pipe right before the merge

 

When I did my research into this subject I tested a range of different primary diameters, merge points and merge angles.

Relative to the Nismo Y-pipe (which merges at the very end of the Y-pipe), dyno testing showed it was better to merge closer to the engine. ...But not too close.

Changing the merge distance changes the merge tuning frequency relative to the engine. You don't want to go too high or too low in frequency or it would lose "area under the curve".

As for the primary diameter, diameter made a good difference too.
If the Y-pipe was connected to a stock system, 2.25" primaries were best.
If the Y-pipe was connected to a high performance exhaust, 2.5" primaries were best.

As for the collector outlet diameter, of course it is best to hook up 3" to 3" or 2.5" to 2.5". Assuming a high flow system is attached behind the Y-pipe, The best performance (or least resistance) is obtained with a 3" collector outlet.

Of course the collector merge angle is an important factor too. Merge angle affects the magnitude of cross bank scavenging. You can't have too much scavenging but that's a another subject.

 

I just picked up an HR Y-pipe from a local guy who has an '08 Nismo Z and just put aftermarket exhaust on it. I'll try to put it on soon if the weather warms up at all lol.

Price = for FREE!

 

Be patient and keep looking. Took me a few weeks to find one. Price will start to increase...supply and demand.

 

Since it was fairly nice out today, I got to put the HR y-pipe on finally. I noticed a slight difference in exhaust note - sounds a little smoother and deeper at idle and when I was revving it in the driveway, but not night and day or anything.

I'll give it a week or so for the ECU to adjust before I make any judgments about performance. While I didn't feel any instant different in power while taking it up through the gears, I did notice a slight difference at very low RPMs such as when pulling out from a stop or low RPM cruising. Before the car would sometimes buck a little when pulling out or I felt that I almost had to slip the clutch, but now it appears to have some more low end and pulls out with less throttle input and way smoother. Also when you get on it hard at say 2000-2500rpms, the car doesn't jerk like it used to it just smoothly pulls up to speed.

I'd say most of the improvement thus far is just being smoother power delivery, not so much more power in general. There is less vibration and noise while driving too.

BTW - revving VQ35 with no y-pipe for the win LOL. I think I skeered some neighbors this morning hahaha.

 

I wonder if someone could take the heatshields off the HR Y and post pics of what it looks like.

 

There is a gap between the two shields which allows you to peer in at the exterior of the pipes. I couldn't see any evidence of any sort of crimp bends. Peering in through the front near the flex sections revealed no evidence of shrinking down of the pipe. As you can tell by the heat shield shape, the HR y-pipe has a far less aggressive y-pipe bend compared to the DE y-pipe.

 

My performance shop is holding a 2008 HR Y-Pipe for me until I can get the money together. I cannot wait to get it installed.

 

so nobody done this with an 04 coupe w/ an 08 hr y pipe yet? or know if it would fit on a 5AT?

 

I second this. I'd really like to know if all this stuff fits on an 04 5AT.

 

^ Dem1k had an HR Y-Pipe on his coupe. It fits. I also know that his coupe is 5AT and that it's pre-06 by the tail lights on his ride.

 

word son!

Yeah, I had it on my '05 AT, bolts up like a charm, so go for it!

`John