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  #1  
Old August 27th, 2008, 12:56 PM
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Question NRP Y-Pipe

Does the NRP Y-Pipe offer better flow than the stock Y-pipe? (I have the NRP cat back on my D90 now) I have the NRP Y-pipe in my garage, but I haven't had a chance to install it...
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  #2  
Old August 27th, 2008, 09:37 PM
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What are the cats they use?
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  #3  
Old August 27th, 2008, 10:13 PM
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I just got one of NRP's latest Y-pipes - I had to wait for it but I think they were undergoing some changes with the manufacturer/supplier.

I installed it a few weeks ago and have put at least 1000 miles since (road trip to VT). The build quality looked very good - 403 stainless tubes. The flanges looked a lot better than the stock setup, welds looked like they pentrated well and were smooth. Bends were very nice. I heard they are using stainless for the weld wire now so it shouldn't rust there either. I have some pics of them next to the stockers - I'll download them if anyone is interested.

Fitment was also good - the cat shield is close to the frame on the passenger side but there is still about an inch clearance. They seem to flow better than the stockers I took off but they were old and rewelded a few times. I feel like the throttle response was better too which is very nice. The note is nice too - wife still think it's loud but I love it.

Overall I'm happy with the full NRP. Not sure if they helped with the MPG and I can't tell exactly (my odometer is broke) but I got around 14-15 MPG on my trip to VT and back.
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Old August 27th, 2008, 10:57 PM
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NRP was purchased by Rovers North some time back......
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Old August 27th, 2008, 11:11 PM
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Which means they're probably made in China out of low-grade Russian stainless buy oppressed Uigurs.
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Old August 28th, 2008, 11:54 AM
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Question

My NRP Y-pipe is about 6 years old, taken off another D90. They have about 70,000 miles on them. I wonder if they are any better than my stock Y-pipe (only about 20,000 miles on them)? My NRP Y-pipe is definately not made from stainless steel. They are rusty. But, if they flow better than the stockers, maybe it's worth the time to install them...
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  #7  
Old August 28th, 2008, 12:01 PM
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The NRP Cat Back system on my ST is perfect... shiney and looks new. It has been on the truck before I've owned it, which has been 6 years.

My SW has the y-pipe back and it is very discolored. But, I am sure that this truck was stored outdoors most of its life.

I have been very happy with the NRP stuff.

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  #8  
Old August 28th, 2008, 12:16 PM
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Edit to my post - it's 304 SS not 403. I posted later at night plus I'm jump between this site and the bike forums where I'm used to talking about 4130 chromo for frames. I knew that Rovers North purchased NRP - but I think Rovers North switch the supplier who makes them - based on the west coast I think but not far as far west as China
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Old August 28th, 2008, 12:24 PM
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Do you notice any performance improvements over the stock Y-pipe?
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  #10  
Old August 28th, 2008, 12:29 PM
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I would wait until your stock is shot before replacing it. You're honestly not going to get any noticeable gains from an exhaust system on a defender.

I bought a complete system a while back and installed it. Sounds great. One cat started sounding like a tin can inside was shaking so I drilled a small hole and stuffed it with stainless wire, then used some muffler repair to seal the tiny hole. That stopped the sound. I drilled small holes through he flat part around the cat and pop-riveted them together firmly. Good as new.

I would consider painting it because it will rust.

I think they used to advertise it as a "stainless" system... which would have made sense for the $1300 that it cost. I'm not sure what it is made of now, but the only stainless on mine is muffler to tip.

Custom exhaust shop is the way to go IMO.
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  #11  
Old August 28th, 2008, 12:39 PM
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I don't think I would bother painting it. I noticed the NRP Y-pipe has smoother bends and has twin tubes coming from the exhaust manifolds to the cats. I thought this may increase flow, resulting in more power...
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Old August 28th, 2008, 12:55 PM
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Theoretically yes... realistically no. It might have a placebo effect, but your Defender's HP bottlenecks are not on the exhaust, they are on the displacement and camshaft. I tried doing everything to increase HP before I got my 4.6. Honestly it is still a dog. Just the nature of the Rover V8... not much we can do about it.

Maybe you can go from 188 to 190 hp... variables such as outside air temperature and whether or not you are running A/C will make more of a difference than the exhaust/cats. Sorry to be so pessimistic, but it won't really change anything. I wasted money and trying different HP boosting mods before getting my 4.6.

Anyway, you have a good spare y-pipe... I would keep it fresh and just use it when the stock cats are gone.
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  #13  
Old September 6th, 2008, 12:22 PM
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Thumbs up

Heath,

I understand that dumping $$$ into the 3.9L motor to obtain HP will result in diminishing returns. It's been a month since I turned a wrench on the Rover...I had to get my fix...

Well curiosity got the best of me and I installed the NRP Y-pipe. The exhaust has more of "throaty" sound and I feel the engine has more pep. The NRP has smoother bends and the entry and exit cat tubes are on center with the cat (I think this would result in better flow), unlike the LR cats which are offset. I also replaced all the fasteners with stainless. Overall, I like the way it sounds, it's got more pep...I like it...


Cheers...
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Old September 6th, 2008, 01:46 PM
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I have it on mine, and I love the sound. I'm like the HP grinch :-)
It's worth it just for the sound!
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  #15  
Old September 6th, 2008, 05:35 PM
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Quote:
Originally Posted by Heath
I have it on mine, and I love the sound. I'm like the HP grinch :-)
It's worth it just for the sound!

You guys are absolutely right. There is no HP gain but the sound is nice. I was working with a local exhaust expert. We were planing on designing a full exhaust system for my 90. After breaking down the benefits of the exhaust he concluded that there is very little to gain in our exhausts. They are not like a toyota exhaust were the manifold is essentially one pipe from the start and all the flow is crammed into a narrow y-pipe. There's a lot to be gained in a toyota system.

Also, you need to look at what you are using it for. If you want HP you may lose some torque. Most of us want torque.

My plan. Let the stock system do its time. When its done replace it with custom y-pipe and high flow cats which will not make any difference in power but may sound better.

If someone sees it differently, let me know.
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Old September 6th, 2008, 06:46 PM
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All the NRP systems I have ever installed were lower grade 516 stainless, not 304

The muffler itself is 304 but the pipes are 516 and will rust together in time. In New England Defender we have had to cut a number of system off because they will no longer come apart for service items.

The system is better than stock though.
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  #17  
Old September 6th, 2008, 07:28 PM
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What sort of gains and longevity are you getting out of your ROX systems?

I have never thought of an exhaust as really a way to get more power on a NA gas burner. I think my Rover has ample power and the Magnaflow I have on it sounds good. You can only polish a turd so much, aftermarket SS is not the way to go.
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Old September 6th, 2008, 08:09 PM
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Quote:
Originally Posted by Heath
...I tried doing everything to increase HP before I got my 4.6. Honestly it is still a dog. Just the nature of the Rover V8... not much we can do about it.
Are you saying the 4.6L is a dog?
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Old September 6th, 2008, 09:28 PM
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Quote:
Originally Posted by ECR
All the NRP systems I have ever installed were lower grade 516 stainless, not 304

The muffler itself is 304 but the pipes are 516 and will rust together in time. In New England Defender we have had to cut a number of system off because they will no longer come apart for service items.

The system is better than stock though.
The NRP Y-Pipe I put on my 90 a month ago had 304 etched on the tubes. Like I said before, it's a clean piece with mandrel bends/kinks and good fitment.

I agree that the exhaust isn't going to do much with these trucks. I changed mine as I wanted some better sound, the stock exhaust was really rusty and the stock Y pipe had been welded a few times and I thought there were still some exhaust leaks.
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  #20  
Old September 6th, 2008, 10:26 PM
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Is everyone getting the NRP y-pipe from Rovers North and are you paying $1439.00 for it?
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