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Discussion Starter #1
On Saturday morning my brother an I installed the Crawford Plenum and High-Flow CATs, the Nismo Exhaust, ZTube, and JWT Pop-Charger. Here are my impressions on each:

JWT Pop Charger:
Very easy to install. Not a perfect fit for the FX (and maybe for other cars too). The heat shield just kind of sits in the car and is only really attached in one location. We installed a felt pad where the filter touches the heat shield. The filter too is only attached in one location, which is why it rests on the heat-shield. Even so, I have no doubt that this is an effective mod, but if you want the "polished" look, go for the Stillen instead.

Install Notes: When you cut and reuse the original rubber accordian piece, make it as long as you want. The place where you cut is smaller diameter, and this part goes INSIDE the Ztube. This is just rubber inside rubbery plastic, so you can't make the clamp too tight or you'll be squeezing the accordian piece out of the ztube. this is why it's nice to make the overlap as long as you can. The original larger opening goes OUTSIDE the MAF.

Z Tube:
Pretty straightforward.

Crawford Plenum:
The Crawford plenum is slightly bowed from when it cooled after welding. This is not a big deal, just use 2 gaskets and some liquid gasket if you want to be extra sure. The engine cover will not fit back on without flexing over the plenum.

Install Notes:
The engine coolant circulates through the plenum to pass federal emissions startup test. Basically, this requires that a car warm-up in two minutes. My brother recommended leaving this off the plenum to keep the intake air cooler. You will have to connect the two hoses to each other somehow.

Crawford CATs:
High flow cats have less than half the resistance of the stock cats. Instead of 2 cats (one dense and one "sparse"), there is just 1 "sparse". Also, they weigh about 10 pounds less each. With the stock exhaust, this mod barely changes the exhaust volume at all. I highly recommend this MOD compared to a cat-back exhaust. You can sell the palladium from your stock cats for about $100 if you know the right people :roll:.

Install Notes:
Surprisingly it is not too hard to remove the cats. On the Y-pipe side there are 2 bolts on each which are easy to remove. At the headers, there are 3 nuts. One of the nuts can be removed easily from under the car with about a 12-inch extension. The other 2 can be remove from above the engine by using all of your socket extensions and then some. And, a universal joint makes things easier. You will definitely need 2 people. Installing the high-flow cats you must use a bolt&nut combination, so you will need a short 14mm wrench to hold the bolt in confined areas while the other person tightens the nuts. If you are also installing the z-tube, do the cats while the intake is off.

The heat shield on the left CAT was much closer to the car than on the right side. I'm not sure why. When the engine is under load, the CAT was hitting my car and vibrating. We ended up chiseling off the heat shield on the left side. We tried a torque-strap on the motor but it didn't help. It is probably also possible just to bang on the heat shield with a hammer to make it clear, but we didn't have time to try this and have it fail.

NISMO Cat-back:
The installation for the cat-back is really simple. It takes about 30 minutes to change the exhaust. But my wife and even myself did not care for the louder exhaust note. I have no idea what this would sound like with the original CATs. But with the high-flow, it is a bit too loud for this type of car. I removed the exhaust on Sunday. If I had left it on, I would have needed another hanger to hold it up over the cross brace under the car. Also, the tips should be extended 7 inches for the FX35, or 2 inches for the G35. Extending the tips would probably make it quieter inside the car too.

FOR SALE: G35 Nismo CAT-BACK EXHAUST. I paid $950 + 80 shipping. Make me an offer (@nc.rr.com, e-mail buchu). I can deliver in the Raleigh or Richmond area personally.
 

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Good review. Interesting idea on the plenum (coolant line); I hadn't heard that one before. Can you give more details on this and exactly what you think it does for you?

You are now the second person to remove the Nismo exhaust due to the sound. Looks like our stock exhaust with the high flow cats and maybe a Y-pipe is the best route.

D- or S-, please move this the the FX35 mods section.
 

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Moved by me to------> FX35 Engine Mods

I would love to see pics if you got any 8)
 

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Discussion Starter #4
I've heard two explanations for the coolant going through the throttle (or nearby).

1) For the same reason that exhaust gas is temporarily recirculated, the throttle is heated. This is to make the car warm up faster and pass federal emissions testing. NOT state inspections, which do not require a cold car of course.

2) Ice? I'm not too sure about this explanation. But someone told me it was to melt ice on the throttle. Doesn't make sense because it comes after the throttle body on our car.

The coolant is 165(175?) degrees, right? So this would probably be heating the intake air slightly. Hot air is less dense, so that's why we made this change.

It could be that the coolant flow is turned off automatically by the car at some point. Anyone know?
 

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Discussion Starter #5
I'll try to get some pics posted. Requests? Which Y-pipe has the same diameter as the stock exhaust? TIA.
 

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dinofx35 said:
Which Y-pipe has the same diameter as the stock exhaust? TIA.
None (actually, there MIGHT be one that does {have to hunt the Z forums}, but I think that'd pretty much defeat the purpose, anyway). You can simply bolt the larger Y-pipe to the stock mid-pipe (the flanges match up), but the abrupt step in pipe diameter from larger to smaller causes some funky turbulence and bad sound. IssaFX on FA put on the RT cats and Nismo exhaust and eded up just keeping the Y-pipe off the Nismo (the rest was sold to Ak1nza). He mated the Nismo Y-pipe (you can do this with the separately available Fijitsubo) to the smaller diameter stock mid-pipe by cutting off the end of the mid-pipe and welding a portion of the G35 extension tube for the Nismo exhaust onto the end in such a way as to make a tapering piece to step down in diameter from the larger end of the extension piece (which matches the Y-pipe) to the smaller mid-pipe diameter. He's quite happy with the results.
 

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Discussion Starter #7
MustGoFastR said:
You can simply bolt the larger Y-pipe to the stock mid-pipe (the flanges match up), but the abrupt step in pipe diameter from larger to smaller causes some funky turbulence and bad sound.
Yes, I'm hearing this sound now sometimes when my car is cold. I still have the Y-pipe installed. One possible reason is that I'm using the smaller diameter size stock gasket, and where the larger y-pipe connects, the inner-most part of the gasket is not touching anything on one side, so it may resonate. And then of course there's that abrupt change in diameter ;-) which probably bounces back sound.

The stock center pipe is already a little tapered. I guess you could modify it to make it really tapered.

Do you think changing the Nismo center resonator or adding a second/bigger one would make it acceptable?
 

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did you guys do this in a shop or in your garage? just wondering if you had this on a lift, or were on a creeper underneath :D
 

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dinofx35 said:
Do you think changing the Nismo center resonator or adding a second/bigger one would make it acceptable?
That's what IssaFX was going to do, but he tried the mid-pipe mod first and that solved the problem.
 

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Discussion Starter #10
bradical said:
did you guys do this in a shop or in your garage? just wondering if you had this on a lift, or were on a creeper underneath :D
I wish. We did it all in the driveway. We used a jack to raise the car up just a bit on one side so we didn't have to hold our breath 8). For some of the nuts you had to approach from above the car anyway.
 

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Great review of the mods Dino. I haven't installed the Nismo exhaust which I purchased off Issa yet. The G35 extension piece was on backorder for a week and just shipped out today. Coming from CA it should take this entire week so I'll probably get it Friday or next monday.

Anyways both you and Issa installed the Nismo exhaust with high flow cats and the y-pipe. I don't have the Y-pipe or the cats so my set up should be much quieter then the both of yours.

I won't know until I get it installed next week. I'll try to post up as well I can how the new exhaust sounds compared to the old.

You never really explained what the sound with the RT cats and y-pipe was. Do you think you could try? So I can have a reference as to what you guys think is 'too loud'? Was it droning in the cabin or 'fart can' loud?

TIA
 

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I'll look back in my FA PMs when I get a chance and see what Issa said about it. The only consideration with what you are doing as opposed to the others is that just adding the mid-pipe and muffler section will only give you a difference in sound; the performance gains are primarily in the cats and Y-pipe.
 

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Discussion Starter #13
The cats and y-pipe are slightly more metallic or "tinny" sounding, and also a hint of deepness probably due to the larger diameter of the Y-pipe. It is not much louder at all during normal driving. For me, there is still the issue of the abrupt diameter change and perhaps some higher tones are coming from this and the gasket.

Keep in mind that there is the lower growl of the all new breathing setup from the other mods. I would say that the change in exhaust volume almost equivalent to the change in air intake volume, just a bit louder.

As you rev to redline, the air intake gets louder faster.
 

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Discussion Starter #15
smiles said:
Did you sell the NISMO already?
I replied to two interested buyers this weekend but have not heard back. I have not sold it yet.

Someone on My350Z.com said that he installed the Nismo and his wife didn't even notice. So apparently the high-flow cats really make the difference in loudness.
 

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dinofx35 said:
Someone on My350Z.com said that he installed the Nismo and his wife didn't even notice. So apparently the high-flow cats really make the difference in loudness.
If that's the case, then you went the right route; the cats have much better gains than the exhaust.
 

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Discussion Starter #17
MustGoFastR said:
dinofx35 said:
Someone on My350Z.com said that he installed the Nismo and his wife didn't even notice. So apparently the high-flow cats really make the difference in loudness.
If that's the case, then you went the right route; the cats have much better gains than the exhaust.
So when are you getting yours? Once I get my UR pulley I'll have the upper hand ;-). Just joking. If I sell my exhaust to a Z-owner, I'll reuse the G-35 extension to adapt a BULLET y-pipe to my FX. Hopefully no audible changes.
 

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Cats & Y-pipe are next on my list as far as performance goes, but I may want to do the rear sway bar first.
 
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